Do you want to say it as a color vector or a color name? I'll assume the latter.
It's pretty trivial code...
default
{
state_entry()
{
llListen(0,"",llGetOwner(),""

;
}
listen(integer c, string n, key k, string m)
{
m=llToUpper(m);
if (m=="RED"

llSetColor(<1,0,0>, ALL_SIDES);
if (m=="GREEN"

llSetColor(<0,1,0>, ALL_SIDES);
if (m=="BLUE"

llSetColor(<0,0,1>, ALL_SIDES);
if (m=="BLACK"

llSetColor(<0,0,0>, ALL_SIDES);
if (m=="WHITE"

llSetColor(<1,1,1>, ALL_SIDES);
if (m=="YELLOW"

llSetColor(<1,1,0>, ALL_SIDES);
if (m=="CYAN"

llSetColor(<0,1,1>, ALL_SIDES);
if (m=="MAGENTA"

llSetColor(<1,0,1>, ALL_SIDES);
if (m=="GREY"

llSetColor(<0.5,0.5,0.5>, ALL_SIDES);
}
}
It should be something like that. If it doesn't work, bug someone else to fix it
