Microsoft released the "Color Printing" extension for Visual Studio 2010! By default, VS 2010 prints only in black and white; this extension restores support for printing code in color.
Installing Color Printing requires VS 2010 Pro, Premium, or Ultimate (the Express editions don't support extensions). You should be able to simply download and install this extension from the VS Gallery or via the Tools menu->Extension Manager.
Once you've installed, you should be able to print as you typically would -- simply use File->Print or press Ctrl+P. No extra steps are required. You might notice that the print dialog looks slightly different, but it should be very similar to print dialogs you would see in VS or other applications:
Download: Color Printing extension