How can I first sort by color & then in alphabetical order in ssrs?
The order by clause in your SQL query should have worked. 

Since it isn't working that means that something else is interfering with the sort order.  

The next place to look is in your Tablix Properties under sorting.

Then look at any Group Properties. Make sure you check each row. 

If you still can't find it, right click on the report in Visual studio and view code. You can then Ctr-F and search for "Sort" and find any sort expressions in the .rdl.

If you find an object you want to look at, you can then use search properties to select the object by name.