The shah may have left, but his palace is intact, and his doleful servants and loyal Imperial Guards already are longing for his return.

This was the message conveyed to foreign reporters taken today on a rare tour of Niavaran Palace, the home of Shah Mohammad Reza Pahlevi, Empress Farah and three of their children. It was a message apparently aimed at countering the belief of many Iranians that the royal couple stripped the palace of priceless pieces of art and other furnishings before flying abroad Tuesday, and that the trip was more than a temporary holiday.

Besides the propaganda effect, the tour provided some rare insight into the way the royal family lived, their pastimes and interests.

The furnishings are often luxurious and ostentatious, but sometimes relatively simple and practical. Numerous paintings and photographs hang on the walls, mostly of members of the immediate family.

The visit was organized by Hossein Amir-Sadeghi, the 29-year-old son of the shah's former chauffeur who declares himself "extremely monarchist," and who seems to have come out on top of some bitter infighting with the Information Department of the Imperial Court.

"The shah himself is a dervish-type," Amir-Sadeghi said before leading the group of reporters through the 15-year-old palace in North Tehran. "He doesn't have any interest in decorations. What yo see is the empress' taste."

The palace is a modern three-story structure of gray stone blocks. Across a courtyard stands an older but smaller building, the residence of 18-year-old Crown Prince Reza. The palace is approached by a long drive-way leading from the main entry gate, where soldiers of the elite Imperial Guard stand with bayonets fixed.

When the visitors arrived, three shah loyalists, two women and a man, were crying outside the gate, pleading with the soliders not to let the palace fall into the hands of anti-shah mobs.

In any case, the grounds seemed amply protected. On a driveway inside the compound, out of sight of passersby, sit two Soviet-built armored personnel carriers mounted with machine guns. In an enclosed area nearby, according to palace officials, are a number of British-made Chieftain tanks that also belong to the guard.

"Everything in the palace will be protected," said an Imperial Guard major at the main gate. The "members of the guard were saddened by the king's departure because we think he is a good man. In five or six months, the people will realize that. Then maybe he will return."

The major said demonstrators drove by the palace Tuesday shouting and honking their horns to celebrate the shah's departure, but that guardsmen scared them away by firing into the air.

Inside Niavaran Palace, a huge entrance hall is covered with expensive Persian carpets. At the far end is a private theater where the shah and his family often watched feature films. Amir-Sadeghi said the shah preferred "light entertainment," especially Westerns, while the empress enjoyed "cinema verite."

Reserved for the royal couple were two white leather armchairs separated by two telephones atop a glass table. Behind them were about 30 green upholstered chairs for guests. The royal couple's evenings were mostly private.

"The shah is not a great entertainer," Amir-Sadeghi said. "He's not exactly gregarious or fun-loving. He's a workaholic. He is not a lonely man. But his work is his life and his life is the nation. He has little time for frivolity."

When the shah did entertain, the young courtier said, he enjoyed playing bridge with "a few old school friends."

Beyond the movie room is a two-story library stocked from floor to ceiling with books in several languages, notably art volumes preferred by the empress. Other works range from Dante to Henry Miller.

Standing near the library's fireplace, surrounded by a relatively simple modern sofa and armchairs, Amir-Sadeghi recalled the major heads of state whom the shah has entertained in the palace.

"Last year President Carter spent New Year's Eve here," he said. He added bitterly, "We've been having it rough ever since he put his foot in this country, both diplomatically and literally."

The young, well educated chauffeur's son, who has unexpectedly been cast into the limelight in recent days as the shah's de facto spokesman here, then waxed political. He blamed the shah's downfall on his "liberalization," which he believes was all but forced upon him by Carter. He called the imperial court a "creep parade."

"I've never seen two such able people surrounded by such a lot of cronies and illiterates and corrupt people," he said. "Without the institution of the monarchy, there's not going to be a country left in a very short time."

Among the more attention-getting furnishings in the palace were tapes-tries, including one given by the late French president, Charles de Gaulle; several antique Chinese cabinets, and drawings by Modigliani and Chagall.

Also remarked upon were a new videotape player and a large-screen television set in an anteroom outside the shah's private study. Among the cassettes stacked next to the equipment was a Japanese tape entitled "Bye-Bye Baby."