Can you travel, absolutely you can. Is it a wise thing to do, probably not. You should avoid traveling abroad if you are on OPT. You are in the process of applying for 140/485, which means you haven’t applied yet and you’re still on OPT status. The best thing to do would be to wait till you get your green card. If you must travel, then apply for travel document I-131 while you file for your 140/485. Good Luck!!