Yes and no. The problem I think you are running into is that the canned reports that come with CRM are all written in standard T-SQL for the query - but in order to use a custom report in CRM it must use FetchXML to construct the query.
Clearly this sounds a bit strange since you just downloaded the report from CRM Online - but the but of the box reports are special in that regard.
So even though you are simply wanting to change a color - that still puts this in the area of a custom report. So you would be looking at converting the T-SQL to FetchXML prior to re-uploading it.
Create Reports for Microsoft Dynamics CRM Using SQL Server Reporting Services