The example Use MeasureCharacterRanges to see where the parts of a string will be drawn in C# shows how to determine where the characters in a string will be drawn and then draws them individually. This example uses similar code but it draws each character in a randomly selected color.

The following code shows how the program draws each character.

// Make a brush with a random color.
using (Brush the_brush = new SolidBrush(RandomColor()))
{
    // Draw the character.
    e.Graphics.DrawString(txt.Substring(i, 1),
        the_font, the_brush, rectf, string_format);
}

This code creates a solid brush using the Color returned by the RandomColor method. It then uses that brush to draw the character.

The following code shows the RandomColor method.

// Return a random color.
private Random rand = new Random();
private Color[] colors =
{
    Color.Red,
    Color.Green,
    Color.Blue,
    Color.Lime,
    Color.Orange,
    Color.Fuchsia,
};
private Color RandomColor()
{
    return colors[rand.Next(0, colors.Length)];
}

The code declares and initializes a Random object and an array of Color values. The RandomColor method itself simply picks a random color from the array.