Seal the concrete with concrete sealer, prime it with a concrete primer, and paint the steps with concrete pain, using a paint roller. Even just painting bare concrete can give it a significantly more cheerful and finished appearance. Choose white for an open look, or give the steps an eclectic look with a bright paint or even a neon color. The paint will dry darker than it goes on. If you do more than one coat, allow the paint to dry thoroughly between each coat.
Or, cover a clean and level set of concrete stairs with tile, using a thinset mortar to hold them in place. Tiles come in a number of different styles, materials and textures, and they add a classic touch to your basement stairs. If you choose tiles with a high gloss finish, they can open up the stairs by throwing back more light.
Or, cover the treads of your concrete basement stairs using vinyl tread covers, held in place with a two-part epoxy. Vinyl tread covers give your steps texture, and while they do not cover them completely, they do interrupt the unrelieved gray of the steps. Use vinyl tread covers when you want to maximize the utility of your concrete steps while providing safer passage for the people going up and down them.