I wouldn't worry about a template. Build your own presentations. You can learn everything you need about effective presentations from google searches and other resources on Amazon. Don't worry about football themes -- if that's all they remember, you didn't do it very well. In other words, it is the content that is important and the ability to put across content is the same in football training as it is in any other type of training.
I use black slides for almost everything. But different colors work OK too.
