To set a calendar color for a specific project, go to the Overview section and click on the Settings on the top of the sidebar on the right. Select one of seven color options from the Color drop-down menu in the Project Settings section. All of the events on the calendar for that project will now appear in your chosen color. They will also be in this color on the All Projects - Calendar section. Additionally, each project event from the All Projects - Calendar shows the name of the project to the right of the event description.