Change the color of the calendars for the Calendar and/or LockInfo from the Settings.app.
The application shows a live preview of the color in both the Calendar application and LockInfo.
Note: LockInfo won't show the correct colors until a respring. The Calendar will show it after completely closing the application from the task-switcher if open and re-opening.
Note: This application automatically update the colors and currently there is no option to go back to the previous/original values
git website: Calendar Colors
No icons are added to your home screen. Configure options from the Settings app.
See the Screenshots below