First go here:

D:\Steam\SteamApps\common\left 4 dead\left4dead\materials\correction

Then select two files: ghost and ghost.pwl. Remove them



That's it. Now instead of blue vision is normal as the survivors



Before


After

First go here:

D:\Steam\SteamApps\common\left 4 dead\left4dead\materials\correction

Then select two files: infected and infected.pwl. Remove them




That's it. Now instead of orange vision is normal as the survivors


Before

After

If you have installed maps "Dead Run" and/or "Cold Fear" or another custom campain then you need to disable or remove them otherwise the infected vision will default

P.S. I advise you not to delete all the files, just move them to another folder, if something goes wrong they can be returned