The color grey has various shades and can be represented in different color models. In the RGB color model, grey can be achieved by equal amounts of red, green, and blue light, resulting in values like (128, 128, 128) for medium grey. In the CMYK color model, grey is often represented by a percentage of black, with values like 100% K. The hexadecimal color code for grey is typically #808080 for medium grey.