Hi! There are a lot of art and coloured train in Moscow metro. So, you even vizit Tretyakovskaya gallery in train, or train with rocket building in USSR, or history train about WWII, movie train and much more. There are a lot of facts in the walls inside and you can go and read this.
One of the train is located in the dark blue line, called Arbatsko-Pokrovskaja line. Train called "S.Ya.Marshack" with sonets of Shakespeare: