Are you perhaps printing in draft mode? From the menu, select Tools -
Options - Print tab, see if Draft Output is ticked. While you're there, see
if Background colors & images is selected (in case that's what's missing).
If neither of these addresses the problem, does the document display colors
correctly when you choose File - Print Preview?
What version of Word is this? And, can you describe the document so we know
what's not working... is it all text? Are images printing in grayscale
rather than color?