I think this is what the colors mean: "The protests have caused strong differences of opinion in Hong Kong society, with a "yellow (pro-occupy) vs. blue (anti-occupy)" war being fought, and unfriending on social media, such as Facebook". There is a note about Green, which I don't quite understand. I think those are "under review"
Green as I understand it should be neutral. Unsure if it applies to this context as well.