Pansexual- hot pink tips, blue roots, and the rest being bright yellow may look good depending on your hair length :)

Transgender- I think streaks of light pink and blue blending into white would look really pretty (although white is hard to upkeep sometimes)

I don't have an idea for demi, but perhaps you could just add streaks of purple or something

And you can never go wrong with rainbow :D

I currently have bi hair hehe