If you take a look at the Moss Motors catalog for MGB parts, there's a section that attempts to list and describe the various colors that MGBs were painted during their 18 year production run. John Twist, guru of all things MG, worked to provide accurate written descriptions of MGB paint colors. While they were informative, terms like 'muddy orange' were a bit of challenge to create in the mind's eye.
Another long-time MG enthusiast, Paul Tegler, has created a web page with photographic examples of MGBs in all their colors. Paul has even set up a screen calibrator to help make the photos more accurate. You can find Paul's MGB colors here. And for you Triumph fans, Paul has created a page of Triumph Spitfire colors, too.