In the same way that a soup can is mass produced and marketed, Warhol is stating that a celebrity can be designed and mass marketed to the public. The color versus the black and white makes one think about the difference between the market image of a celebrity and the harsh reality of their life.
Warhol created pieces about mass media because he didn't want to make art for art's sake. He believed in business art, in which art pieces are designed and mass produced in an efficient way in order to make a profit. He took the ideas portrayed in his art pieces, like "Marilyn Diptych", and applied them to the presentation of the art. Instead of creating something original and singular in its presence and its creator, Warhol hired people to create his art and payed them to mass produce his works.