This seems closely related to How does a lens affect the saturation of a picture?.
Some older lenses I've seen contain the word "Color" in the name, such as Color-Yashinon and Color-Skopar (the latter is still made by Cosina Voigtländer). Does this mean the lens is optimized for color film? Can a lens that produces good results with black-and-white film exhibit poor performance when used with color film?
Although jrista answers the question in a basic way, he does not explain WHY a lens may be optimised for colour.
As far as I'm aware any given lens will produce an 'adequate' image on both colour and B&W film, as its the same focusing plane and film area, however chromatic aberration is far more prominent in colour (its very hard to spot in B&W, and appears as a mild blur)
Therefore a colour optimised lens will have a more correction-based design, hence the marking.
(I have not seen a modern 'colour' marked lens so must assume all are to some degree colour optimised now)
I have a feeling that the "Color" portion of the name is simply marketing, as the lenses in question were released at a time when color film was not as common.
If there were any technical differences, they would probably be focused on reducing chromatic aberration (CA). Reducing CA is done by modifying the lens design and/or materials so that different color wavelengths all have the same focal point. While this is beneficial for black and white photography as well, because it increases the sharpness, it is not a cheap problem to fix. However, since the fringing effects are more noticeable for color photography, the extra cost would be more easily justified.
The following is an example of the difference of chromatic aberration for b/w vs color:
The first (while not a fantastic image) is decent, while the color version has clear flaws.
The word "Color" in the name does indeed refer to color film. In the case of Yashinon, it does not necessarily mean it is "optimized" for color film, simply that it is capable of being used with color film. The lens is also fully capable of producing black and white photographs as well. At the time, in the 1960's and early 1970's, Yashica cameras were more widely used for black and white photography, so explicitly calling out viable color film compatibility was kind of a big deal.
It wasn't until the 1970's that color film really came into common use, and COLOR-Yashinon lenses started appearing before that time. It seems one of the more popular Yashinon lenses was the COLOR-Yashinon DX 1:1.7 f=45mm lens, commonly paired with the 1973 Yashica Electro 35 GSN.
I don't have a lot of information at hand for the Color-Skopar, and there seem to be "classic" as well as modern lenses that bear that name but are not related to one another outside of the reuse of the name in a modern Leica lens design. I gather, however, that the classic versions came out of the 1950's (an even earlier era for color consumer film), and I assume the purpose of the word Color was the same as in Yashinon lenses.
There are two aspects to that:
The coatings (or maybe even choice of optical glasses) will have been made in a way that makes them relatively color-neutral. Do not forget that film had a fixed white balance. Some early lens coatings (single coating era) create a noticeable blue or yellow color cast.
As mentioned in other answers, chromatic aberration will be corrected to a certain level. While it would seem that heavy CA can be deleterious to a sharp B/W image too, remember that B/W era photographers loved using strong filters (yellow, green, red...) to modify tone mapping - which had the side effect that most of the light striking the film was in a narrower wavelength band, which mitigates CA to a degree (you could get a very sharp image with a lens not corrected for CA at all... if you lit your scene with monochromatic light!).
