If you evaluate or print the following string you get what you want:

    "\!\(\*StyleBox[\"text\",FontColor->RGBColor[1, 0, 0]]\) \!\(\*StyleBox[\"text\",FontColor->RGBColor[0, 0, 1]]\)"

![Mathematica graphics](https://i.sstatic.net/AitIl.png)

This is a single string and it contains color information for different substrings.

    Do[Print@"\!\(\*StyleBox[\"text\",FontColor->RGBColor[1, 0, 0]]\) \!\(\*StyleBox[\"text\",FontColor->RGBColor[0, 0, 1]]\)", {5}]

![Mathematica graphics](https://i.sstatic.net/fnL7g.png)