I was able to figure out how to apply different color for the event using a call to DayPilotCalendar1_BeforeEventRender, however, I ran into another issue.  So I have a calendar control that is bound to the daypilotcalendar so I can change dates, however, this no longer works after the change I implemented for applying different color.  Here the code I added to the Default.aspx:
    protected void DayPilotCalendar1_BeforeEventRender(object sender, BeforeEventRenderEventArgs e)
    {
        int id = ((int)e.DataItem["id"]);
        switch (id)
        {
            case 1913:
                DayPilotCalendar1.Theme = "calendar_green";
                break;
            default:
                DayPilotCalendar1.Theme = "calendar_traditional";
                break;
        }
The calendar_green gets applied to the event with ID 1913 and calendar_traditional gets applied to everything else, but I can no longer click on my calendar control to change dates.  Do you know why adding the DayPilotCalendar1_BeforeEventRender would cause my navigation to break?