There are many different species of octopus and some change color and pattern more than others. You can find a lot of interesting pics under Journals and Photos - have a look at Carol's G2 (corw314) to see lots of colors and patters. Not many people keep dwarfs so we haven't had many pics of them. Eventually maybe you can photograph your octopus.
As far as I've been able to find out, most color changes are for making the ocotpus invisible, either while on a rock or while hunting. Bright red (a brownish red) can mean anger or being upset. This I've seen in two different O. briareus. White can also mean fear - it just depends on the species.
So maybe you can stop the frequent water changes due to inking for a while. Remember that Gus will be skittish for a while, so move slowly when you're around him.
He's had a lot of excitement already, so he needs a quiet life for a while.
Keep us posted,
Nancy