While I was watching F-1 as a young guy, the majors all stuck to the national colors in GP and GT. As more countries recovered from WWII, there were many more countries represented. Then, nations with teams that had been active in GP for decades dropped out, like Belgium, and so on. Brazil became the only yellow, even though the Brazil yellow was very pale, like the Talbot Lago above, and the darker yellow of Belgium made occasional appearances from time to time.
This is the best table for the national colors I know of, and there are incomplete parts in it.
http://en.wikipedia.org/wiki/List_of_in ... ing_colors