I had the same thing happen- the update makes the "Digital Vibrance" slider in the nVidia Control Panel go to ~90%. Bringing that slider back down to 50% should solve your problem. Hope that helps!
Thank you for posting this! I updated my brother's MacBook last night and noticed the colors were very saturated... I thought it was just me, but now I see that it's not. Thanks for posting the solution. I shall do this when I get home.