The color of the iCloud birthday calendar cannot be changed.
This is a limitation of the system-generated birthday calendar on iPhone. We would love to change it ourselves, but it is currently not possible.
As soon as Apple allows it, we will support it right away.
For now, there are two workarounds:
- Hide the iPhone's birthday calendar
- Create your own "Birthdays" calendar and add each birthday as a regular event
We appreciate your understanding that this is a limitation of iCloud itself. If the specification changes, we will support it immediately.