If she is very closeminded and confident in her ways you probably won't make any difference, but if you suspect she is at all open to discussing her views you could get a really interesting discussion going. It's very human to be xenophobic, but it's a mark of intelligence and empathy to be able to rise above it. You could bring it up gently, commend her on her honesty and ask her directly why she feels it's "natural" to be a little racist. Maybe she has some bad experiences to tell, maybe she's just repeating what her parents and friends think, maybe she never has been challenged on it before.
Most of the time we do react by rote, and it takes a little jostling to see that our reactions are irrational, and can have negative effects we haven't thought about. Like offending coworkers. If you accept that her reaction is natural for her but is based on misconceptions you have a chance of changing it. Depending on her personality of course.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett