Can an international student travel outside of USA immediately after graduation, and then come back to USA?

I am an international student in USA. I need to travel outside of USA immediately after graduation. I hope to be back in one month, and then apply for OPT (Optional Practical Training). Is there any problem during re-entry? I have travel signature on my I-20, and the signature is valid for next one year.Can an international student travel outside of USA immediately after graduation, and then come back to USA?you cant do re entry as you think. It involves many formalities. If you want to apply for opt you should apply before going out of the country