Cognizant pays them hourly; they are referred to as "contractors" multiple times in the article, while the word "salary" does not appear.

Hourly employees are still employees. Salary v. Hourly is completely different distinction from employee/contractor (you can have an hourly or fixed monthly/annual contract rate, and you can get either model as an employee, though salary is more common if your pay and working conditions make you an FLSA exempt employee, since otherwise you might need to be treated as hourly for overtime and certain other things anyway.)