That CSS property is all you need it works for me...When previewing in Chrome you have the option to see it BW and Color(Color: Options- Color or Black and white) so if you don't have that option, then I suggest to grab this Chrome extension and make your life easier:
The site you added on fiddle needs this in your media print css (you have it just need to add it...
media print CSS in the body:
@media print {
body {-webkit-print-color-adjust: exact;}
}
UPDATE OK so your issue is bootstrap.css...it has a media print css as well as you do....you remove that and that should give you color....you need to either do your own or stick with bootstraps print css.
When I click print on this I see color.... http://jsfiddle.net/rajkumart08/TbrtD/1/embedded/result/