Talk to her and tell her that while her intentions were good, you just don't think those colors are good for you. I bought my boyfriend an orange (bright orange, kinda rusty looking) shirt a few years back cause I thought it would look wonderful with his dark skin tone (he's Hispanic). He thought otherwise, so he took it back for a color he liked. I now make jokes about it...even though I was a little disappointed that he didn't like it. But, like sunnygirl said, if she's cool, she'll understand.
good luck! I think you should get bonus points for not wanting to hurt her feelings
Jadey