These are energetic expressions and I don't think these are symbologies based on a matter of likeness. In understanding and perceiving the world, everything expresses a certain unique and distinctive energetic characteristic. For example, the energies of Venus are quite different from those of Pluto, and certain gods have energies that are akin to venusian energies, while others to plutonian energies. Same with colors; each color has a distinct energetic signature and is characterized by a certain type of energy.