Whatever its composition, do not put your sheath in the dryer. It would come out unusable.
Once thoroughly washed, do not twist your sheath either to wring it out, at the risk of relaxing it and reducing its level of compression.
Hang it out in the open air, with clothespins, or better yet, let it dry flat so that it regains its initial shape and effectiveness.
Once dry, do not iron it.
You can fold it and store it in your dressing room if it is made of nylon or polyester and without seams or closing system. If it is made of latex and/or is equipped with hooks or zips, do not fold it but hang it with a suitable hanger in your closet. You can also store it flat on a shelf. But don't roll it up on itself.