I treat my purses like perfection. As in I baby them completely.
The hubs was a sweetie and got me a gorgeous Tory cross-body for Christmas one year. Well, the sucker turned blue after several wears. After searching everywhere, I turned to Pinterest. Much to my surprise I found a secret that worked for me. (I say "me" because it worked for me but may not work for you; test on your purse first, pretty please).
Buy some face wipes with a very low amount of alcohol. I bought the store brand from my local Kroger. Test the wipe on a small portion of your purse. Wait 2-3 minutes and make sure it does not turn. If it works, wipe gently over the color-turned portions of your purse until cleaned to your liking. Enjoy!