WW colors are red and blue, more recently black. Of course it's better to not tie it to US at all. But if she doesn't have those colors, it won't look like WW. If her costume was actually brown, she would just look like a common Amazon, not Wonder Woman. You have to see the character. If it wasn't that way, Superman's costume could be black, yellow, red, anything... The darker tone of his costume (thought it's too dark IMO) and the removal of any US reference is enough to accept it as just a blue costume instead of a flag. The same applies for WW. US hasn't trademarketed red and blue colors.
The entirely red costume of evil Diana from Injustice is already dreadful.