Create a pivot chart with a count on the favourite colour field
Use a connection field instead of multiple choice field. In a separate table, you would have a set of colour records with a Count field to check how many times they have been referenced.
Export the data to Excel and perform the summarisation there
You could make a “reports” page for yourself. In there create a Table View which uses source data that only contains that color. Then when you open the page it’ll show the entire list plus the total number of records (Showing 1 - 25 of total). Or you could make it into a Search View and choose which color you want to check at will.