Bring a large pot of salted water to a boil over high heat. Add the thin spaghetti and cook according to package instructions, usually about 8-10 minutes, until al dente. Drain the spaghetti in a colander and rinse it under cold water for 1-2 minutes to cool. Set it aside in a large mixing bowl.

While the spaghetti cools, dice the tomatoes, zucchini, cucumber, green bell pepper, and red bell pepper into bite-sized pieces.

Add the cooled spaghetti and all the diced vegetables into the large mixing bowl. Toss everything together until well combined.

Pour a generous amount of Italian dressing over the mixture and toss until evenly coated.

Cover the mixing bowl and place it in the refrigerator for at least 2 hours to chill.

Before serving, toss the salad again and spoon it into serving bowls or a platter.