Show Group Title instead of Item Text in Calendar View


I have a Calendar View:

You see that each day has an “Item #” and is colored by a Group Titles.
Blue Items are “Group Title ONE”
I would like to show on those days not the “Item #”, but the Group Title itself, so instead of having on each day “Item #”, I will see “Group Title ONE” or “Group Title whatever”

Can you please guide me how I can achieve this?
Maybe using Integration APIs? an App?

Thank you very much,