First of all there is currently no official Android client for the Mumble project.
Once upon a time … there was one client, named mumble-android and it was created by pcgod. All but one of the available clients are based on the client from pcgod, which hasn't been developed since November 2010. Some screenshots can be found here.
Although the source code was always available on GitHub, it has never been free licensed. So all clients based on that one were never in a legal state. To clarify that, pcgod made a last commit, see his commit message.
The one client not based on pcgod´s work is Plumble 3.0 which is a complete rewrite of Plumble (legacy) (2.0) (which based on pcgod´s client).