Just to make sure: can the printer actually print in color? And by that I mean, assuming it is a color printer, that the settings are set to color printing and not set to black and white.
If the HTML page is in color, a color printer should print it in color as well, unless the printer settings say it should print in black and white only. Those settings can't be overridden via CSS I'm afraid.
Oh, I just read your post again: I see the images are being printed in color, but it's just text and icons? That is weird... might still be settings though.
And @j450nhughes is right, the more code we can see, the easier it is to pinpoint the problem :)