Command: color

Syntax: 
color [on|off] - turn color on or off
color extended_color [on|off] - turn extended colors on or off
    Extended colors may not work with all clients.  Enable at your own risk.
color with no arguments will take you to the color menu, where you may set
    your color preferences.  You will be given a list of all message
    classes available to your character, as well as all available color
    codes.
color <class> <colorcode> - set a color directly, without the menu

The following colorcodes can be used to change the color
of most messages:

$RED$ - red             $HIR$ - pink
$GRN$ - green           $HIG$ - light green
$YEL$ - orange          $HIY$ - yellow
$BLU$ - dark blue       $HIB$ - blue
$MAG$ - purple          $HIM$ - magenta
$CYN$ - cyan            $HIC$ - light blue
$HIK$ - grey            $HIW$ - white

Also:
$0$ - normal, resets color
$BOLD$ - bold, usually white