A presidential order to cut down on graduate school draft deferments is being prepared, Lieutenant General Lewis B. Hershey, draft director, said yesterday in Washington.

Testifying before the Senate Armed Services Committee, Hershey said the order should make it more difficult to push deferments into permanent exemptions. It is now fairly easy for graduate students to get through the 18 to 26 year-old draft age bracket on deferments and never be drafted.

Hershey said last night at his home that he did not know anything about the contents of the presidential order that is being written or when it would be released.

But he supposed that the order would not affect students already in graduate school.

He added that he was aware that many students make plans for graduate school well in advance and pre-enroll. He did not think pre-enrolled students would be touched by the order either. "But I'm just guessing," he emphasized.

Hershey appeared before the Senate committee to urge that the present draft law be extended beyond its June 30 expiration date with few changes.