General:
* My colleague is very knowledgeable about the project.
* I'm going to lunch with my colleagues today.
* We had a productive meeting with our colleagues from the other department.
Specific Situations:
* My colleague helped me troubleshoot a technical issue I was having.
* I need to collaborate with my colleagues on this presentation.
* I received a birthday card from a group of my colleagues.
* My colleague suggested a great new restaurant for our team lunch.
* I'm learning a lot from my colleagues in this new role.
Formal:
* I appreciate the support from my colleagues on this project.
* I'd like to thank my colleagues for their hard work and dedication.
Informal:
* My colleague is cracking me up with their jokes.
* I'm going to grab a coffee with my colleague after work.
* My colleague is the best person to ask for advice.
These are just a few examples. The specific way you use "colleague" will depend on the context of your writing.