Foreign Minister Moshe Dayan said today that if Egypt is not prepared to sign a separate peace with Israel, and if the other Arab states continue to boycott the Cairo talks, then the Cairo conference at the present level would "exhaust its role" within a week to 10 days.

Coming on the eve of the Israeli delegation's departure for Cairo, Dayan seemed somber, and in marked contrast to the optimistic tone of Prime Minister Menahem Begin's press conference yesterday.

Dayan said there was room for optimism in that both Israel and Egypt were prepared to be forthcoming and showed a real desire to reach an agreement. But the time was "not united" for Egyptian President Anwar Sadat, he said.

"I think that President Sadat is expected by his people, and by his own moves to deliver something, to [WORD ILLEGIBLE] something within a week to 10 days. If he wants to do that he will face some problems," Dayan said.

Speaking before the Foreign Press Association, Dayan said that Israel was approaching the Cairo talks prepared to discuss all problems with Egypt, including a separate peace; and also, in a general way, problems such as the West Bank, Gaza and the Golan Heights that concern other Arab states. Egypt, however has said it does not want to sign a separate peace with Israel and Egypt also says it is not authorized to negotiate for the other Arab countries.

Dayan pointed out, however, that neither the Arabs nor any of the Americans working on Middle East problems had ever suggested or agreed upon a partition of the West Bank between Israel and the Arab's and he left no doubt that the call for total withdrawal, especially from some traditionally Jewish sites outside the 1967 borders, was unreasonable. Nonetheless, he said, the issue of Jerusalem and the problem of the Palestinians is negotiable.

Dayan did exclude any negotiations with the Palestin Liberation Organization. If it were to show up in Cairo, he said, "Israel will not be there."

He said that while the Egyptians or other Arabs were free to introduce the issue of a Palestinian state, Israel would not consider it in the same spirit of flexibility and compromise as other issues. He said that a palestinian state was "unacceptable to Israel."

Dayan showed little receptivity to a suggestion that an Israeli concession now might make it easier for other Arabs to join the Cairo talks.

"It is not a birthday party where you give gifts," he snapped. "We are not discussing peace and the permanent boundaries of our country . . . for generations and generations to come."

Therefore, in Dayan's view, "the Cairo talks can be about procedure and other issues one way or another for some time and then Egypt will have to negotiate on a separate agreement between Egypt and Israel" or the other Arab countries will have to join.

Since there is little chance of Syria's changing its mind. Dayan said, and since Lebanon lacks "real independence and couldn't go against the wishes of Syria, "that leaves only Jordan available to talk with Israel and Egypt.

Secretary of State Cyrus Vance, in Amman today, is trying to persuade King Hussein to join the Cairo talks, Dayan said. "Let us hope he will persuade the Jordanians . . .", Dayan said. "Otherwise the Egyptians will have to go on with just themselves and Israel."

In answer to questions, Dayan said that a future partition of the West Bank was "not excluded" from Israel's negotiating position. He said he had been authorized by Begin to say on behalf of the government that a partition of the West Bank or Gaza was not, in Israel's view, a workable solution "but if the other parties suggest it will discuss it."

Dayan said the Jewish settlements in the occupied territories should not and would not represent a bar to Israeli withdrawal and that if partition was agreed upon, the Jewish settlements on the Arab side would either be removed or left there consent.