Manually choose color-coding for boards displayed in Dashboard calendar view

This is a wall I have come up against recently. I have a calendar widget that is designed to show my team dates from multiple columns (e.g. start date, end date, action date, etc.). Ideally I want to be able to colour code these based on which column the dates are from but I cannot see this option in the ‘Colour By’ settings - it only offers the options to colour by other status columns when really what I want is for dates from the start date column to be red, dates from the end date column to be green, etc. (for example). It would be fab if this functionality could be added. Thank you!