Well, the colors are an indication of the chin's genetic makeup--homo (short for homozygous) means the chin carries two of the same color gene, hetero is the opposite, meaning the chin carries two different color genes. So a homo-beige would carry two beige genes, and thus would only contribute beige genes to its kits, but a hetero beige will be able to contribute either a beige gene or a standard gene, giving a greater number of color possibilities for the chin's kits.
Some colors are dominant to others, meaning if the chin carries two different color genes, for example standard gray and violet, the dominant color, standard gray in this case, will show up in the animal's color, while the other gene doesn't show up in the chin's coat. This animal would be called a "carrier" of the violet gene.
TOV, or touch of velvet, is also a carried trait, which can alter the appearance of the chin's fur, giving them the darker color on their faces, shoulders, and back.
It can get kind of complicated. That's one of the reasons it's important, as a breeder, to keep track of your chin's pedigree, so you know what each animal might have in its background. This will allow you to make good choices on how to pair your animals together for breeding.
I hope this helps clarify a bit. Do you have any questions about specific colors?