There are several ways you could go about coloring text. Three of the more common ways are:
1. Create the text as a sketch, then fill the sketch with hatching. If you lower the spacing on the hatching enough, it looks like a fill. The down side, you can only use one color for the text and it can cause a slower regeneration on rotation and in drawings.
2. Create your text on your part as a sketch and then either make it a small protrusion or small cut. You will need to watch out for what your model's resolution is as this can cause problems if the feature is too small. You would then be able to color the individual surfaces any color you want. However, be aware that this does create a feature on the part.
3. The final method you could use is a custom appearance with the text included, but you will have to be careful how you place it on the model and it will not show up on any drawings containing the part (unless you use shaded views) and cannot be dimensioned.