要件に合わせて個別に予定の背景色を変更するには、BeforeAppointmentFormatイベントで、条件に応じてe引数のBackColor／BackColor2を設定します。

◎サンプルコード（VB）

Imports C1.Win.C1Schedule
Imports C1.C1Schedule

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ' 予定の作成
        Dim app As Appointment = C1Schedule1.DataStorage.AppointmentStorage.Appointments.Add()
        app.Start = DateTime.Now
        app.End = app.Start.AddHours(2)
        app.Subject = "予定A"
        Dim app2 As Appointment = C1Schedule1.DataStorage.AppointmentStorage.Appointments.Add()
        app2.Start = DateTime.Now.AddHours(1)
        app2.End = app2.Start.AddHours(2)
        app2.Subject = "予定B"

        ' 最初に表示する時間帯の指定
        C1Schedule1.Settings.FirstVisibleTime = New TimeSpan(DateTime.Now.Hour, 0, 0)
    End Sub

    Private Sub C1Schedule1_BeforeAppointmentFormat(sender As Object, e As BeforeAppointmentFormatEventArgs) Handles C1Schedule1.BeforeAppointmentFormat
        If e.Text = "予定A" Then
            e.BackColor = Color.DarkRed
            e.BackColor2 = Color.DarkRed
        ElseIf e.Text = "予定B" Then
            e.BackColor = Color.LightSalmon
            e.BackColor2 = Color.LightSalmon
        End If
    End Sub
End Class

◎サンプルコード（C#）

using C1.Win.C1Schedule;
using C1.C1Schedule;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            //  予定の作成 
            Appointment app = c1Schedule1.DataStorage.AppointmentStorage.Appointments.Add();
            app.Start = DateTime.Now;
            app.End = app.Start.AddHours(2);
            app.Subject = "予定A";
            Appointment app2 = c1Schedule1.DataStorage.AppointmentStorage.Appointments.Add();
            app2.Start = DateTime.Now.AddHours(1);
            app2.End = app2.Start.AddHours(2);
            app2.Subject = "予定B";

            //   最初に表示する時間の指定
            c1Schedule1.Settings.FirstVisibleTime = new TimeSpan(DateTime.Now.Hour, 0, 0);
        }

        private void c1Schedule1_BeforeAppointmentFormat(object sender, C1.Win.C1Schedule.BeforeAppointmentFormatEventArgs e)
        {
            if ((e.Text == "予定A"))
            {
                e.BackColor = Color.DarkRed;
                e.BackColor2 = Color.DarkRed;
            }
            else if ((e.Text == "予定B"))
            {
                e.BackColor = Color.LightSalmon;
                e.BackColor2 = Color.LightSalmon;
            }
        }
    }
}