There isn't really a set scheme across all of capoeira, different schools tend to have differing colours. I was part of the Senzala Capoeira school. I got my first level white cordao at my first batizado and the highest level was red worn by Mestre Gato. The white cord led to confusion when training with other groups, as in some schools the Mestre wears white, so you can imagine their surprise when a bunch of beginners walk in wearing the same rank as their master.

interesting in that the two most effective of all such systems (wrestling and boxing) don't go by rankings but merely results.

muay thai is about the same, although i think that within a gym there is an informal/unofficial belt system.