I've had a chance to talk to Marc Okrand recently and he explained it to
me. These are my own words describing the situation.

He agreed that his wording was bit confusing. KGT is correct saying that
there is no noun for color in the sense of "What color is that?" or "Red
is a nice color." The new word {qalmuS} is used to distinguish the
colorfulness of pictures, for instance. He pointed at a color photograph
and said "That one has color" and then at a black'n'white photo and said
"that one has not."