Leasing providers are used to customers asking for permission to put small graphics or even full body wraps on their cars in order to showcase a business effectively. However, whether or not you will be allowed to do so depends on the rules of the finance provider funding the agreement.
If you want to sticker up your lease car, be sure to mention this in the upfront negotiations with your chosen provider. It may be that you are allowed to do so, but be under guarantee that the wrapping will be done by a reputable company in order to ensure that no damage is done to the paintwork of the car when it comes to removing it.