Colored shirts are otd
But seriously, with the exceptions of a few basic rules about what must be covered, the way one should dress, whether on Shabbos or during the week is completely based on minhag. There are many places where it would be inappropriate to show up in shul in anything other than a suit. On the other hand, there are places in the world where one would look very foolish wearing a suit in shul, and it would therefore be inappropriate to do so.
No halacha sefer will give a blanket statement about what color shirts are acceptable.