Otis, Are you worried about you not enjoying the process because you don't like the fabrics, or about your customer, who might not like the final result because the fabrics don't go together well? If it's the former, you can always bow out. If it's the latter, perhaps it would be a good idea to get all of the fabrics together, lay them out next to one another, and gauge her reaction to them. If she continues to love it, then she'll no doubt love the final piece. There is no accounting for taste. I've seen quilts in some magazines that I wouldn't make (in those colors) if it was the only quilt I could make!
Cheers!