Try the following solution:

First, enable custom drawing of the resource row headers, by setting Calendar.CustomDraw to CustomDrawElements.ResourceViewRowHeader. Then handle the Calendar.Draw event. The event handler can have an implementation similar to the following:

private void calendar_Draw(object sender, CustomDrawArgs e)
{
	if (e.Element == CustomDrawElements.ResourceViewRowHeader)
	{
		Contact contact = e.Resource as Contact;

		ItemCollection c = calendar.Schedule.GetAllItems(
			DateTime.MinValue, DateTime.MaxValue, contact);
		bool selected = false;
		foreach (Item i in c)
		{
			if (calendar.ItemSelection.Contains(i))
			{
				selected = true;
				break;
			}
		}

		if (selected)
		{
			Rectangle b = e.Bounds;
			b.Width -= 1;
			b.Height -= 1;
			e.Graphics.DrawRectangle(Pens.Red, b);
		}
	}
} 

The above code presumes that the resources in the calendar are contacts. If you are using different resources, perform the necessary modifications. The code draws a red border around the header of the resource row containing selected items. If you need some other kind of visualization, you may have to custom-draw another CustomDrawElements, such as ResourceViewCell.

Meppy

This can happen if you are not grouping by contacts (e.g. you are grouping by locations or general resources). In this case you will have to cast to the appropriate type. For example, if you are grouping by location, you will have to modify the code in the following way:

Location location = e.Resource as Location; 

Meppy

You can use a similar approach. You need to set CustomDrawElements.ResourceViewCell as a value of the Calendar.CustomDraw property and modify the contents of the Calendar.Draw event handler in a way similar to the following:

if (e.Element == CustomDrawElements.ResourceViewCell)
{
	Contact contact = e.Resource as Contact;

	if (e.Date.TimeOfDay.Hours >= 8 &&
		e.Date.TimeOfDay.Hours <= 16)
	{
		Rectangle b = e.Bounds;
		b.X += 1;
		b.Width -= 1;
		b.Height -= 1;

		Brush brush = new SolidBrush(Color.FromArgb(200, Color.Red));
		e.Graphics.FillRectangle(brush, b);
		brush.Dispose();
	}
} 

Hope this helps.

Meppy