Be honest with her. Let her know you are attracted to women of color, but you see her as so much more than just that. It's not all that different than noticing a woman because of she was wearing a nice dress, then getting to know her and finding out she is more than what she was wearing that night. Yes I get I'm making a horrible metaphor comparing a dress and someone's race, but just taking things to the extreme to try to make a point. First impressions do count, but after that first impression if you find the person is a jerk your out of there, but if your lucky and they are a great person, they why would the reason you were first attracted to her be a big deal, as long as you really like who they are as a person.