Open the Color picker trough button click

Hey guys,
I’m making a custom editor and I would like to have a button that, when pressed, opens Unity’s color picker.

    private Color someColor;

    // Method invoked when the button is pressed
    private void ChangeColor()
    {
        //Here I want to set the color 'someColor' to the Color picker's value
        //someColor = ColorPicker()
    }