The Amiga CLI and Shell support the standard ANSI escape sequences for enabling color. They are limited to the available colors and those colors are taken from the palette as mentioned above.
You can set foreground colors with:
echo "*E[3Xm"
where X is a number from 0 to 7
and background colors with:
echo "*E[4Xm"
where X is a number from 0 to 7
You can also do both on the same line using something like
echo "*E[4X;3Xm"
If you need to reset the styles use
echo "*E[0m"
You can also do other things like bold "*E[1m" and I think the Amiga also supports underline and italics. Those are values in the 2-6 range but I can't remember which one is which.
If you are doing a lot of shell manipulation there are some cool values you can do with these escape sequences. *E[ is the same thing as CSi if you look up these ANSI escape sequences elsewhere.
