Bring a large pot of lightly salted water to a boil; add penne and cook, stirring occasionally, until tender yet firm to the bite, about 11 minutes.

Heat oil in a large skillet over medium heat, and cook and stir sausage, onion, green bell pepper, red bell pepper, orange bell pepper, and mushrooms until vegetables are tender, about 10 minutes.

Stir diced tomatoes, tomato sauce, minced garlic, garlic powder, oregano, basil, salt, black pepper, and red pepper flakes into vegetable mixture; bring to a simmer and cook, stirring occasionally, about 10 minutes.

Drain pasta and spoon onto plates and top with sauce mixture.