As my master, you should know - I'm fairly flexible when it comes to... matching preferences. <The demon gestures to themselves.>
If you're not a fan of this, then I could always just stick to a singular appearance that I have that will haunt your dreams. One of your mentors should be able to teach you how to adjust your summoning ritual.
Of course, if you want to leave it up to me... Well, I can guarantee a good time either way.