Well, if you like a guy (as in, just one) that doesn't define a sexuality at all. If you like guys in general it depends on how you feel about yourself.. Are you a trans WOMAN or a TRANS woman? Like, are you first and foremost a woman and just happen to be trans? Or is being trans an integral part of your gender identity? I have seen trans women identify as straight, gay, lesbian, etc. so there's ample precedent for each way. Just go with what you feel and if at some point it doesn't feel right anymore you can change. But if you're pan anyway that certainly makes that problem a lot easier. 😅
(Don't say "transwoman" though please. Trans is an adjective and writing "trans woman" as a single word can seem like it's somehow not the same gender as a woman. A lot of trans people don't like that.)