Can I mix latex paint into concrete
While you probably could, this wouldn't be a good way to try and match a color.  It would likely effect the setting performance of the concrete and you'd never match the color of the paint.  On top of everything else, it would be much more expensive than the alternatives - all you really need is the pigment and everything else that makes up the paint is essentially wasted.

For coloring concrete it is much better to use products that are specifically designed for this - either a concrete dye mixed into the concrete itself, or a concrete stain applied afterwards.