The biggest improvement would be to get your colleagues to agree to buy a grinder and write out a simple set of directions for the amount of beans to grind for each pot. Since this is just drip machine or a large percolator, the quality of the grinder is not hugely important like it would be for pour over or espresso. A basic Baratza Encore would be more than good enough.

Cafe Bustelo, Eight O'Clock Coffee, plus the Costco and Aldi brands mentioned by others should all be a big step up from pre-ground Folgers.

The key is to grind before each brew instead of using pre-ground.