Some early days design work getting a feel for it.
The 'parti-colour' uniforms were both useful in being highly visible, and also humiliating as they gave a prisoner the appearance of a jester. These were given primarily to those serving life sentences (which more often than not were not actually ones entire life) while those on shorter sentences wore entirely yellow uniforms. Yellow was also the chosen colour as in the symbolism of the day it was associated with disgrace. Those who displayed prolonged good behavior might be allowed a grey uniform.