Yep. Are there varieties that are specially bred for colour or for hobbyists?Do you mean the standard annelid worms you can collect outside in the dirt? If so, I'd say that should be fine. To keep humidity up, some people will add a bit of shredded newspaper every now and then and the worms will munch on that too.
I'm mainly keeping them as axolotl feeders, but they're also incredibly interesting to me.I don't know about colors though I do know there are green bait worms. Don't know anything about them. Just wanted to add one bit of advice that is really good to follow: The less you disturb your worms, the better off they'll be. I keep African night crawlers in a 20 gallon long with isopods and many other microfauna. They are happiest when their tunnels aren't disturbed. I still turn most of the soil about once a month to check on decomposition of the various underground food and to make sure it's moist throughout, but otherwise they get left alone. Worms seem to like to just do their own thing.
Also, think about why you want to keep worms as the many different varieties have different uses. Red wrigglers and a few types of night crawlers, for example, are great composting worms. There are a few species of worms that do better or are required to be at a much lower temperature than room temperature. Some worm species aren't hardy at all and some will out breed your space if you're not careful.