Piano Phase, composed by Steve Reich, is a fascinating piece of minimal music for 2 pianos (or marimbas).
It uses 3 short musical phrases, with 12, 8 and 4 semiquavers respectively, that are repeatedly played by the 2 pianos, starting out in parallel (piano 2 fading in over some repetitions). Over the next repetitions piano 2 speeds up very slightly to reach the point where it is one semiquaver ahead to piano 1. This process continues until piano 2 has advanced to the point where it is parallel again with piano 1. This full cycle, together with a fade out/fade in of one piano is done also for the next 2 phrases. Details and a better description can be found eg at Wikipedia.
This rather technically sounding description leads to a very subtle effect how the phrases sound in their shifted positions - every different phase shift sounds subtly different - experience this yourself by listening eg to this performance by Art Murphy and Steve Reich.
My image is a representation of this music - horizontal lines are like the lines of the score for the music, two adjacent rows corresponding to the 2 pianos. Color represents the note pitch; fading from or to black represents the fading of the respective piano.
The 3 different parts corresponding to the 3 different phrases can be seen clearly, separated the the black parts representing the fade out/in of one of the pianos, also visible how the phrases are getting shorter.
The acceleration as well as the resulting new phase shift clearly stand out in the color patterns.
All in all, the representation is faithful to the musical score except for the choice of the repetitions that are given as possible ranges in the original score. I adjusted these so that lines for the different phases result in equal lengths in the image.