Look for a picture of a cowboy on a bucking bull that has a good silhouette. Enlarge it as needed and do the appliqué in a dark solid colour. You could use a sandy marble background fabric and either machine or hand appliqué the silhouette to the background fabric.
There are companies that sell fabric silhouettes if you Google. Some even come laser cut with the fusible on the back already. The problem with those is you might not be able to find a bucking bull.