You have a quite a few options for colored concrete floors.
During the pour you can use:
-Integral Color - This is usually a mix of granules (powder) that is mixed into the concrete truck, and colors the concrete all the way through. Sometimes the batch plants have liquid dyes that I have heard of, but ive only ever used the powdered type. I usually source my own integral color, and put it into the truck myself. Usually the integral color is in paper bags that are supposed to dissolve, but they often dont and will leave defects in your concrete. I always take my integral color, dump the bags into a bucket, and pour that into the truck. With integral color, if you scratch or chip your concrete, you wont really see a color difference. The downside to integral color is there can be variations in color from truck to truck, especially if pouring on a hot day and the concrete contractors need to add more water to the mix to keep it from setting up. Usually integral color costs like $20 per yard of concrete and then the dispatch plant will charge you another $50-$100 for a wash out fee.
- Color Hardener - This is also a powder type mix, that is broadcast onto the surface and troweled in during the finishing process. Color hardener is nice because you get a consistent color across the surface, and it actually makes the concrete surface slightly more durable (hence the name). There are a couple of downsides to color hardener. It is super messy, since you are throwing the powder all over the slab. It will get on whatever is around the slab. It's somewhat tricky to use if you arent familiar with it. A bucket of color hardener is usually $60-$80 and one bucket will usually do 100 sq ft.
After the pour, one your concrete slab has cured for at least 28 days:
- Concrete Stains or Dyes. You can do a "grind, stain, seal" where the concrete would be ground down to open up the cap and then stain it using something like a water based stain or an acetone based dye. And then you would seal it with various different types of sealers.
There are also some more options, but these are the more common options.