The colors in the original were likely so that they could name the characters themselves, and truly create them while following the skeleton provided. It only told how they fit in, not who they were, which meant that they would still be your character. In this case though I'm not sure how much of that I'd be able to retain, since color'ed characters must be secrets from the RPers for the plot to be engaging.

I certainly agree with choosing a character as the culprit. There is no fun in this sort of RP if the GM is in charge of that aspect, and I feel that person would have the second most control over the RP with their actions. The tricky part would be, as I mentioned before, allowing private scenes between their characters and others without revealing the truths to the other RPers.

As for authoritative character.... perhaps, however I feel the dreams/colors fulfill that role, the question still lies in how to deliver it. Does one character see these dreams, making them fill a detective role? Do all colors see the dreams that they themselves take part in?

Ideally the dreams can reveal clues about all the characters, not outright naming one color as the murderer but instead revealing details about each color as the characters both attempt to discover other characters color identities as well as which color/person committed the crime. The crime doesn't have to be murder either, perhaps one character is a 'color thief' and when he steals the colors from the others, they fall into coma's for the duration of the RP? That would avoid the police aspect of the RP.

Beside having a ton of background private RP's going on every time characters are not in a public space though, does anyone have insight onto how we could have background info on these characters to reveal to the RP? The RP could always follow an honor code where we ignore plot details from other private interactions, but this would make the colors scenes far less engaging and make sleuthing feel more mechanical.