Well you need to keep it's humidity up with a dripper and enough mistings. If your cage isn't able to maintain the humidity, you can always cover one or two sides. Some people use plastic shower curtains. Lots of live plants also help keep the humidity up. Do you know what humidity levels Senegals require?
Set up an appropriate living area. Most species of chameleon do not like seeing their reflection in glass, such as an aquarium. Therefore, a screen or mesh cage is best. It offers adequate airflow and eliminates the potential problems associated with glass cages. Vertical area is important in chameleon cages, as they like to climb, so minimum cage size should be no less that 24”L x 24”W x 48”H. The cage should be well furnished with live plants and trees, which are vital to proper Senegal care. The ideal temperature should range from 75 to 98 degrees F, with 50 to 100% humidity for thriving chameleons.
If you do some searching on the forums you can find some really good info on temperature and humidity. Just type in "senegal", and you'll be good to go!