If you add a color that does not exist, Prestashop creates the new color. If you have Pink but you import Pink Gradient, Prestashop creates that new one.
Also if you have Pink but you import PINK, Prestashop creates new color PINK. So I don´t understand why it does not create a color called "4140" unless it does not accept numbers or the Attribute "Color" (not their Values) does not exist. Check the spelling maybe Prestashop calls "Colour" and you call it "Color" and that will give you an error, because you need to have the Attribute before it´s values.
Please, advise.