Cook pasta in boiling water 7 minutes. Add green beans; cook 4 minutes. Drain and rinse with cold water; drain.
Combine pasta mixture, chicken, onion, basil, parsley, and bell pepper in a large bowl, tossing gently to combine.
Combine oil and remaining ingredients in a small bowl, stirring with a whisk. Drizzle over pasta mixture; toss gently to coat.