There, in a mauve room of the Renwick Gallery, filled with paintings and candlelight, Egyptian President Anwar Sadat's pilgrimage to Washington concluded last night with an elegant dinner and a hearty toast. The glittering mixture of Egyptians and Americans, Republicans and Democrats lifted delicate crystal goblets filled not with champagne but a nonalcoholic breed of sparkling white grape juice suitable for observant Moslems. And with their glasses, they raised their hopes and voices for peace.

"It is with great pleasure that we meet again in your country," Sadat said in a toast to Vice President George Bush and the dinner's hosts, Egyptian Ambassador Ashraf Ghorbal and his wife. "It has been a great opportunity to strike a solid friendship."

Sadat called President Reagan, with whom he spent a part of yesterday in meetings, a man of "great moral strength." He said he felt confident that peace was first on Reagan's list of priorities, but made no mention of his suggested negotiations with the Palestinian Liberation Organization, as he had in his toast Wednesday night at the White House. Last night, calling the recent cease-fire in Lebanon "an American achievement," Sadat wished that "the success the administration has attained" so far in domestic affairs "should be repeated internationally."

Bush then returned the Egyptian's message of good will: "We've learned a great deal from your country . . . math, geography . . ." but especially, Bush emphasized, "peace." You're a great friend and partner," Bush told Sadat before the more than 200 guests. Alluding to the work of poet Carl Sandburg, he concluded by saying, "When God made Anwar Sadat, he couldn't have done anything else that day."

The guest list included Secretary of State Alexander Haig and his wife, Pat; former secretaries of state Henry Kissinger and Cyrus Vance; former Chase Manhattan Bank head David Rockefeller; Carter administration national security adviser Zbigniew Brzezinski; current national security adviser Richard Allen; Defense Secretary Caspar Weinberger; Washington Post Co. chairman of the board Katharine Graham; White House protocol chief Leonore Annenberg and her husband, Walter.

Brzezinski explained his presence by saying, "Occasionally I come into town to tell people what to do, so they don't go astray."

Haig reiterated his objection to the United States opening negotiations with the PLO. Asked if he thought such negotiations were likely, Kissinger said, "I don't think they'll do it." Vance would only repeat what Haig had said: "He has said they will not."

While mingling was kept to a minimum during the well-orchestrated evening, the guests seemed to have in common a respect for Sadat. Sen. Edward Kennedy (D-Mass.) said he has been a "great admirer" of Sadat and his "peace efforts" since the two met in Egypt several years ago. He came last night, he said, "to let him know my respect." Alejandro Orfila, secretary general of the OAS, called the display of warmth at last night's dinner "extraordinary." In Arabic, and there was a good amount, spoken over the veal and artichoke, it's called marich jaou , or joyful atmosphere.

The rasmin , or dinner, began with cocktails and hors d'oeuvres downstairs, then everyone filed upstairs and through a reception line to greet the Sadats, the Bushes and the Ghorbals. yamong the political people, a smiling Pearl Baily created a slight stir and seemed to never be standing alone. She wore a brightly colored craftan and two necklaces: one with a pendant bearing the Helbrew word chai , or life; the other bearing the Arabic phrase "Go with God." The first she bought for herself on a recent trip to Jerusalem; the second, said Bailey, was given to her by Sadat's wife, Jehan, in 1974 when Bailey performed at Egypt's Sphinx theater.

Much of the evening's talk turned to Egyptian lore. Kelly Simpson, a professor of Egyptology at Yale, not only conversed in Arabic with Dr. E.L. Naggar, executive director of the World Bank, but joked with waiters about the lobster mer rouge . "Is it really from the Red Sea?" he quipped. But the lobster was from Maine.