You can change the color of each piece. To change a piece’s color, you need to first select it, and, then, click on Change piece color.
You can choose the color from the newly-opened window. You can customize and add colours to the colour bar by opting for a colour and subsequently clicking on Add to custom colours. To choose one of the colours displayed on the screen (not only from the Choose colour window), click on the Pick screen colour button, and, then, select the colour with a click.