CustomDrawCellBackground += Grid_CustomDrawCellBackground;
...
row.Cells[index].CustomDrawFlags = iGCustomDrawFlags.Background;
...
private void Grid_CustomDrawCellBackground(object sender, iGCustomDrawCellEventArgs e)
{
	color = Color.Aquamarine; // Only for testing!!!
	using (Brush brush = new SolidBrush(color))
	{
		e.Graphics.FillRectangle(brush, e.Bounds.X, e.Bounds.Y, e.Bounds.Width, e.Bounds.Height);
	}
}

internal class Grid : iGrid
{
public Grid()
{
	RequestCellToolTipText += Grid_RequestCellToolTipText;
	KeyDown += grid_KeyDown;
	CustomDrawCellBackground += Grid_CustomDrawCellBackground;

	RowMode = true;
	ImageList = GenericImageList.ImageList;
	ForeColor = SystemColors.ControlText;
	SelRowsForeColor = SystemColors.ControlText;
	SelCellsBackColor = SystemColors.ControlLight;
	SelCellsForeColor = SystemColors.ControlText;
	DefaultRow.Height = 22;
	DefaultRow.NormalCellHeight = 22;
	DefaultRowHeightAutoSet = false;
}
private void Grid_CustomDrawCellBackground(object sender, iGCustomDrawCellEventArgs e)
{

	Color color= Color.Yellow; // Only for test!!!

	using (Brush brush = new SolidBrush(color))
	{
		e.Graphics.FillRectangle(brush, e.Bounds.X, e.Bounds.Y, e.Bounds.Width, e.Bounds.Height);
	}
}
}