While learning how to tell color on baby Hollands is as much a matter of first hand experience and understanding the genetics so one can predict possible colors, having a guide can't hurt. Hopefully this will be of some use. This page isn't by colors as most of my photos have the whole litter in them, which actually should help as you can see them next to each other. Before we begin, I'll mention a few little tricks of the trade.
So, on with the photos! Colors listed bottom to top or left to right unless otherwise noted.

Left: 2 days old - All opals except the lynx, which is the 2nd from the top
Middle: 12 days old - Lynx, Opal
Right: 4 weeks old - Lynx, Opal

Left: 2 days old - Lynx, Cream
Middle: 6 days old - Lynx, Cream
Right: 9 days old - Cream, Lynx

Left: 2 days old - chocolate tri, chocolate tri, broken chocolate tort
Middle: 5 days old - broken chocolate tort, chocolate tri, chocolate tri
Right: 9 days old - chocolate tri, chocolate tri, broken chocolate tort,

Left: 1 day old - broken cream, cream (across top), tort, broken cream (half burried), blue tort
Right: 10 days old - broken cream, cream, tort, broken cream, blue tort

Opal, broken cream, cream, broken opal (these two broken creams doe have blue looking ears that would make one think blue tort, however, while it may not be super visable in this photo the color is only around the edges of the ears. They actually grew up to be nice and clean, no smutt.)

Left: 2 days old - lilac, chocolate, chocolate chestnut, chocolate
Right: 12 days old - lilac, chocolate, chocolate chestnut, chocolate

Left: 1 day old - black tri, chocolate tri, broken orange, blue tri, blue tri
Right: 1 week old - black tri, chocolate tri, blue tri, blue tri, broken orange

Left: 2 days old - starting with the heavily marked black tri going clockwise: black tri, chocolate tri, lilac tri, black tri, broken blue tort, broken orange, torted black tri
Right: 5 days old - starting with the lightly marked on the left, going clockwise: lilac tri, black tri, chocolate tri, torted black tri, black tri, broken orange, broken blue tort

Left: 2 days - black tri, black tri, torted black tri, black tri, torted black tri, blue tri
Right: 5 days - starting left bottom to upper right: torted black tri, black tri, blue tri, two black tris, top right is torted black tri

Left: 1 day - four broken opals, and one broken lynx (right on top of the others)
Right: 12 days - The bkn lynx and one of the bkn opals were peanuts, only three broken opals survived.
Left: 1 day - three chestnuts, one black (notice the black has color on the inside of ears)
Right: 7 days - three chestnuts on the bottom, the black on the top