Preheat the oven to 375F (190C). Lightly grease a 9x13 inch baking dish.
In a large skillet over medium heat, saute the zucchini, yellow squash, red bell pepper, and yellow bell pepper until tender and most of their moisture has evaporated. Set aside.
In a medium bowl, combine the ricotta cheese, eggs, half of the shredded mozzarella cheese, parmesan cheese, and Italian seasoning. Stir until well blended.
Spread a thin layer of tomato sauce on the bottom of the prepared baking dish.
Place 3 lasagna noodles over the sauce. Spread one-third of the ricotta cheese mixture evenly over the noodles.
Top with one-third of the sauteed vegetables and another layer of tomato sauce.
Repeat the layers (noodles, ricotta mixture, vegetables, sauce) two more times.
Sprinkle the remaining shredded mozzarella cheese evenly over the top.
Cover the baking dish tightly with aluminum foil and bake for 30 minutes.
Remove the foil and bake for an additional 15 minutes, or until the cheese is melted, bubbly, and slightly golden brown.
Let the lasagna rest for 10 to 15 minutes before slicing and serving.