The reason that Clam Chowder is white in color is because Clam Chowder has milk and cream added to it to give it the consistency that it has.
Without the milk or cream the clam chowder would not be as thick as it is and would not be white.
Also there is meat in clam chowder.
The meat in clam chowder is clam meat as well as cubed salt pork.
So if you're vegan and want to avoid meat then you would not want to eat any clam chowder.
Clam Chowder consists of potatoes, onions, sometimes salt pork, and milk or cream as well as clams and heavy cream, light cream, or whole milk that is the base of the clam chowder.
You could make the clam chowder without the meat if you are vegan but the clam chowder would not really be clam chowder without the meat or clams that are added to it.
Clam Chowder is delicious but I have not tried clam chowder without the meat.
Although it's likely just as good.