Color the datagridview there where it found a difference with SQL

Question

I got some code which makes an SQL query and pastes the result into a datagridview. This works perfectly. The code be seen below:

private void FillInDataGrid()
{
        string cn =     ConfigurationManager.ConnectionStrings["Scratchpad"].ConnectionString;
        SqlConnection myConnection = new SqlConnection(cn);

        string sql =

        "SELECT " +
        " dbo.new.[column1], dbo.new.[column2], dbo.new.[column3], dbo.new.[column4] from dbo.new" +
        "except " +
        "select dbo.old.[column1], dbo.old.[column2], dbo.old.[column3], dbo.old.[column4] from dbo.old"
        ;

        SqlDataAdapter dataadapter = new SqlDataAdapter(sql, myConnection);
        DataSet ds = new DataSet();
        myConnection.Open();
        dataadapter.Fill(ds, "Authors_table");
        myConnection.Close();
        dataGridView1.DataSource = ds;
        dataGridView1.DataMember = "Authors_table";
}

This code displays the values of the row from the new table if it doenst exists in the old table. Now I want to color the cells where they differ. So for example if you have those two tables:

new table:
--------------------------------------
| column1 | column2| column3| column4| 
--------------------------------------
| 1       | 1      | 1      | 2      |
--------------------------------------
| 2       | 2      | 3      | 2      | 
--------------------------------------
| 6       | 7      | 9      | 8      | 
--------------------------------------
| 7       | 5      | 34     | 22     | 
--------------------------------------
| 3       | 4      | 3      | 3      | 
--------------------------------------

old table:
--------------------------------------
| column1 | column2| column3| column4| 
--------------------------------------
| 6       | 7      | 9      | 8      | 
--------------------------------------
| 7       | 5      | 34     | 22     | 
--------------------------------------
| 1       | 1      | 1      | 1      |
--------------------------------------
| 2       | 2      | 2      | 2      | 
--------------------------------------
| 3       | 3      | 3      | 3      | 
--------------------------------------

So this example would show:

--------------------------------------
| column1 | column2| column3| column4| 
--------------------------------------
| 1       | 1      | 1      | *2*    |
--------------------------------------
| 2       | 2      | *3*    | *2*    | 
--------------------------------------
| 3       | *4*    | *3*    | *3*    | 
--------------------------------------

Where the * 2 *, * 3 * and * 4 * would show a color in the datagridview.

Thanks in advance for your help.