It may be difficult to find a designer that's willing to accept the stake of your coin if it's not yet listed.

However, there might be some designers that's willing to take this order in able to add also a design for their portfolio/banner.

Overview of Bitcointalk Designers(Signature,Avatar,etc) Last Update: 09-Aug-2018. Check that list for professional designers and negotiate with those that are accepting token/altcoins.