This is a well known idea in data visualisation -- first articulated by Jaques Bertin back in the 60s (I think). Colour is known as a selective visual variable;

This is a well known idea in data visualisation -- first articulated by Jaques Bertin back in the 60s (I think). Colour is known as a selective visual variable; selective variables are better used to represent categorical data as they "enable us to immediately isolate all correspondences belonging to the same category". i.e. sort your lego by bricks type rather than colour, though sorting by colour will lead to more instagram likes :)