This excellent little VBA macro named ColorToByLayer reads through the current drawing layouts and changes any entity objects that have a color setting that is not "by layer." Changed entities are moved to a new layer named "CBL_" plus the color number. The entity color code is then reset to be "by layer." To use Find and Change Objects by Color Setting,  you need to launch AutoCAD’s VBAide, then select the File and Import File . . . and navigate to where the BAS file is located. The BAS file will load into a module. Select the module in the project window pane and then click the run button (F5 key). The macro ColorToByLayer should be available to run, so click it, and the rest is automatic. This utility is a great VBA example for those looking to learn how to use this marvelous customization tool.