I guess, if you have already finished your credits before April and only your Graduation is on May, then you are all right. Just have a transcript and a letter stating that you have completed your course requirement before April. You can have that letter either from the International Student office or your Advisor or Incharge of the person who is responsible for your academic records.

In that letter, it should be clearly stated that you had completed your degree requirement before April.

But if you are only completing all the degree requirement in the May and applying for H1B in April then think 10 times before doing that. Now-a-days, USCIS is being very strict especially about H1B so do not try to submit any fraud thing while filing your H1B.