Campaigner submitted a new mod: Shiny Pets - Unique Monsters are now colorful! Read more about this mod...
Ignore the Readme on installing for Nightly, the install path changed with the latest update and I didn't even notice. Nightly installation goes into the "Starbound - Unstable/mods/" folder.
If you ever figure out how to change the chance of a monster being shiny, should really lower the odds of a monster being shiny to either 1/4 or 1/8.