That's a difficult one… when it comes to internal feelings, I can only really speak for myself, though of course I can talk about what I've observed in and talked about with other autistic people (mostly women) to some extent?
There are autistic women who go all-out on femininity; you'd have to ask them, but I think a lot of us spent a whole childhood trying to decode the rules and work out how best to follow them, in order to blend in. Once you have the rules (if you can work them out) it's easy to follow them. I guess some enjoy it and it feels natural to them? I guess you'd have to ask them 
But I guess it's possible that sometimes someone feels the opposite sex's rules might be easier to follow…? I don't think it's anything calculating, though.
I think personally it's more of a thing of feeling outside somehow, incapable of instinctively and easily picking up correct social behaviour - I don't fit in as a woman, so where do I fit in? I don't see the point of following this rule or that one, so am I really a proper woman or am I something else - is the reason that I'm not very good at womanning because I'm not meant to be a woman - and why might that be?
When I was younger (preteen/early teens maybe?) I sometimes wished I was a boy, felt like I must be more like a boy that an like a girl, mostly for the pragmatic reason that there was an awful lot of faff and inconvenience and confusion involved in being female. I wasn't very good at playing the female social game and I wasn't weak and silly and dumb and bitchy and keen on dolls and interested in boy bands and all the other bullshit stereotypes I thought I would have to be, and I didn't see the point in pretending to be just so people would like me. I was too clever for all that…
I didn't want to be the stereotyped female and couldn't understand all the complexities of how to navigate them.
I guess when it comes to the way I look, at least, I come across kind of androgynous - despite having enormous boobs 😒, I get told off in ladies' toilets and referred to as "sir" in public
It's comfort and practicality, a lot of how I suppose I must present. I guess I feel more physically comfortable in clothes that are read as "male". Male-stereotyped clothes are generally less constricting and easier to move about in. I can't walk in heels, maybe because of the coordination problems that are quite common with ASD. I don't like makeup because it takes time, feels nasty, and my face looks okay how it is really… it seems bizarre to me to put makeup on except maybe for fancy dress, or masking serious skin problems if you're embarrassed about them. Totally fine with other people wearing it obviously, it just seems… like an odd thing for half of society to feel they have to be doing in order to fit in, and the other half not to do? But it can't just be my clothes; lots of women wear t-shirts and jeans. There must be something about the way I walk or stand or take up space or something that's not right, but buggered if I know what it is 
I'm sorry, that was garbled and didn't really answer your question 😂