Sonia, In this context, I think "all" means "a lot of color or colorful." Are there any pictures for your example?

Hi Sonia, Depending on the context, it can either refer to all of the colors like you mentioned for "every" color, or it can also refer to the entirety of something, such as the case with your examples: "That's where all the color is" and "All of that color that you are seeing there." It's as if referring to "all" pigments of that color, in a way. Example of "all" referring to the numerical amount of something ("every"): ---> Look at all those leftover hamburgers going to waste. Example of "all" referring to the entirety/wholeness of something: ---> That burger is huge--are you really going to eat all of it? Hope it helps :)

It's just a expression. Look at that image: http://joco.name/wp-content/uploads/2014/03/rgb_4096_3.png Now, it's really a colorful one. Here you can use that expression. Look all the colors are here, Even though there are not every color present in that image.