Give the gift of Drupal. All merchandise is 50% off through 2016.
Why is this error generated? Where is public: defined?
public:// is a stream wrapper, its whatever your public files path is.
The problem is with Color module, AT nor PR load this file, Color module does. I can only suggest to try saving the color settings again to generate a new file, and check your file system path, it might be wrong - maybe you migrated and put the files in the wrong place?
Drupal is a registered trademark of Dries Buytaert.