What colour is sweet?

I picked up these four packages at a local coffee shop. I am not an artificial sweetener user, but I am intrigued by the use of colour as a branding tool.

Equal (yellow) is filled with aspartame, Splenda (blue) is filled with sucralose, Sweet'n Low (pink) is filled with sodium cyclamate, and Sugar is filled with, well, sugar.

I am going to keep looking at packages of artificial sweeteners to see if there is some standardization between the chemical and the colour.