Plan, Do, Check, Act
For each process or system, you need to figure out
Plan: What is the target or objective. What is the process intended to do?
Do: How is it done? Procedures, instructions, control plan, etc followed? Do people know how it should be done?
Check: Are targets being met, products made to spec?
Act: if no, are there actions in place to correct/improve it?
You need to think of each process in that way. Process maps are valuable to link it all together. Process flow charts, operator instructions, part drawings, control plans/FMEA. What are the outputs? Who are the customers (and that could be the next internal process).
You really wont find a boxed, one size fits all, internal audit template. Not that would satisfy the standard requirements and benefit your company. You don't want to do anything just to check a box and meet a requirement. When you plan your internal audit, it should be done in a way that will add value to your company.