One of these stocks is up 320% over the past year.Growth stocks are more diverse than you might think. Consider, for example, that Cintas, a company supplying uniforms (and more) to other companies, has average annual gains of more than 25% over the past 15 years. And paint company Sherwin-Williams has averaged nearly 20% over the same period.One of the drawbacks of growth stocks, and especially tech stocks, is that they're often overvalued. But if you look carefully, you'll likely still turn up some seemin ...