Why puppies get different colors?

COLORS & LITTERS

Life, whether human or animal, on earth carry heterogeneous traits. It means that they have two or more different characters. One trait may be visible and dominant and the other may be hidden, or it may be of a mixed trait. Remember, parents of medium height may give birth to a son or daughter of the same height, or  even taller or shorter than they are, as they possess both traits and while one should come from the father and another should come from the mother. The traits of the offspring depend upon what trait each parent contributes. Imagine both father and mother possessing  tall +short genes.

If father gives one tall gene and mother also gives tall, the child would be taller than the parents.

If father gives one short gene and mother also gives short, the child would be shorter than the parents.

If father gives one tall and mother gives short, the child would be of medium height as the parents.

We have come across two different animal coats, either they may be of a pure color or of mixed colors. See a Doberman's color; it will be a black and tan, or a tan, or a special grey shade, called peacock blue.  See a Labrador, it will be a full black or chocolate brown or a fawn (yellow) but not of mixed dots. These bands or shades of color are controlled by specific genes. Some genes may mix up and dilute, some may only patch the color, and some are dominant, which take over and stand out against other colors.

I have put a simple explanation to make you to understand but in reality it is complex. Whatever it may be, if you understand the logic, then you will understand the reason behind why puppies get different colors in the same litter of a multiparous animal.
I share with you here some beautiful pictures of  dog litters, which I hope you will appreciate. 

*The pictures are from net and I have not changed  the name / meta tag of the original owner to respect copy right ownership except resized.