Since we're talking about sensory inputs, colors are known to be finite, and due to the limited bandwidth of the olfactory system those are likely also finite. However, at a glance, there's likely to be more smells than colors, due to the number of possible independent smells versus the number of possible independent colors.
The number of independent colors, for a normal, unimpaired human being is three, arguably four: red, green, blue, and at a very specific light levels an unnamed color that is ultimately a result of overlapping sensitivity regions between rods and cones in the eyes. Each set of cones can independently identify approximately one hundred shades of their respective colors and the rods presumably manage at least ten shades of light-dark separation which results in a grand total of approximately 10,000,000 colors.
[1]
The number of independent smells is less well known, since smell is primarily a way of measuring molecular charge distributions in small concentrations of gases. So, how many unique ways are there to create charge distributions that a human's olfactory sense can detect? That's much harder to count, but one well accepted convention is to group smells into seven categories: musky, putrid, pungent, camphoraceous, ethereal, floral, and pepperminty
[2]. As such, smell will have a larger number of possibilities if at least on average each independent odor can be detected at 8 separate concentrations, and if it is possible to detect each such concentration simultaneously. They do not need to be obviously separate, since red-green mixing in light is perceived as yellow: the mixing of two or more odors can be perceived as a separate odor distinct from its components. It would seem reasonable to assume that at least eight separate levels can be perceived for each of these categories, since that's an exceptionally low fidelity requirements for a sense that can distinguish good food from rotten food and in general in a different way for different forms of expiration of the same food.
As such, smell probably wins.
For everyone who mentioned infinity, there's a finite amount of processing power in a human brain and a finite amount of bandwidth available to the olfactory and optic nerves. If you want to look up which one is likely to be capable of accepting more information, look up which of those nerve groups is larger. It's also worth noting that smell and taste are extremely related, almost to the extent of being the same sense.