As I am unsure what kind of Gaming Platform you are using I will list out both PC and Xbox360/PS3. For XBox360 cheat codes, you can go to [this site][1] 

> To activate cheat mode, pause the game, and select "Extras" and
> "Cheats". Select "Add Cheat" and enter one of the following codes to
> activate the corresponding cheat function. If you entered the code
> correctly, you will hear a sound.

As for the list of Xbox360/PS3 cheats that I currently know of: (I did not add the world codes etc. as you can find these in the website I gave)

> •cheese - gives you $100,000 
> 
> •letsrock - gives you a full set of weapons 
> 
> •runfast - you can sprint forever
> 
> •whatitmeanstome - give respect
> 
> •brains - zombie mode
> 
> •ammojocky - toggles unlimited ammo
> 
> •vroom - your vehicle is immune to damage



As for the PC version, you can check out [this website][2] 

> You can enter cheats by accessing the HUB menu, then the Extras menu,
> and finally the Cheats menu. Entering codes disables auto-saves and
> also will not allow you to earn any in-game Trophies or Achievements
> unless you load a save without the cheats enabled. You can enter any
> cheats below to access the corresponding effects
> 
> •cheese - Puts $100k in your pockets (can be spammed multiple times in
> a row)
> 
> •letsrock - Gives you a full load-out of randomized weapons
> 
> •goodygoody - Removes the Notoriety from you at any time
> 
> •runfast - Your super-sprint doesn't exhaust your Stamina
> 
> •fryhole - All of the dead bodies lying around start to raise up into
> the air
> 
> •vroom - Indestructible cars
> 
> •isquishyou - All cars can now drive over other cars like tanks (can
> only be turned off by reloading a clean save)
> 
> •hohoho - This makes all of the pedestrians either pimps or
> prostitutes (LOVE THIS ONE)
> 
> •mascot - All pedestrians turn into mascots
> 
> •evilcars - Makes all of the cars on the road target you and start
> attacking you



  [1]: http://gamewise.co/games/46318/Saints-Row-IV/Cheats/Cheat-Codes/Player-Codes
  [2]: http://www.ign.com/cheats/games/saints-row-4-pc-122148