I Like Martian Music

There have been a number of interesting theories advanced about life on Mars, but few have equalled Charles Fritch's intriguing picture of the world of Longtree and Channeljumper in its infinite variations, tonal and thematic. The Mars of these two is an old culture, old and finite.
Longtree played. His features relaxed into a gentle smile of happiness and his body turned a bright red orange.
Longtree sat before his hole in the ground and gazed thoughtfully among the sandy red hills that surrounded him. His skin at that moment was a medium yellow, a shade between pride and happiness at having his brief symphony almost completed, with just a faint tinge of red to denote that uncertain, cautious approach to the last note which had eluded him thus far.
He sat there unmoving for a while, and then he picked up his blowstring and fitted the mouthpiece between his thin lips. He blew into it softly and at the same time gently strummed the three strings stretching the length of the instrument. The note was a firm clear one which would have made any other musician proud.
But Longtree frowned, and at the disappointment his body flushed a dark green and began taking on a purple cast of anger. Hastily, he put down the blowstring and tried to think of something else. Slowly his normal color returned.
Across the nearest hill came his friend Channeljumper, striding on the long thin ungainly legs that had given him his name. His skin radiated a blissful orange.
Longtree! Channeljumper exclaimed enthusiastically, collapsing on the ground nearby and folding his legs around him. How's the symphony coming?
Not so good, Longtree admitted sadly, and his skin turned green at the memory. If I don't get that last note, I may be this color the rest of my life.
Why don't you play what you've written so far. It's not very long, and it might cheer you up a bit.
You're a good friend, Channeljumper, Longtree thought, and when Redsand and I are married after the Music Festival we'll have you over to our hole for dinner. As he thought this, he felt his body take on an orange cast, and he felt better.