They light it up orange all the time for a win or for a graduation. The thing special about that is the number "1" is lit up on all 4 sides.
They only light the top portion for conference wins in football. A win vs. OU or A&M and they light the whole tower. Win a national championship in any sport and they put the number 1 on the side facing the main mall (facing towards the capital downtown)
I haven't paid attention to the #1 on all sides thing but I'm assuming that is because this is their 4th football title??
They also light it up orange for a number of academic and texas historical events like graduation, texas independence day, etc... There are many other lighting combos they do with the tower that don't come to mind right away but you can prob find online easily.