Hi
If you are referring to the "Schedule %" available in the out-of-the-box portlets like "Project Analysis Portlet", "Team Member Task Summary Portlet" & "Late Tasks and Milestones Portlet", you can view its range and colors in the query associated with the respective portlets.
Once you identify the query (Navigate to Administration--> Queries), then you need to navigate to "Attributes" tab of the query and select the the "Schedule %" attribute and view the color and range details.
Hope it helps.
Regards,
Srikanth G