Depending on the size of the job and your level of experience spraying turf, there are several options.
When applying Endurant Turf Colorants, most garden sprayers, backpack sprayers, airless
sprayers, skid sprayers with reel and boom sprayers will all work for painting grass.
Entry level garden sprayers and backpack sprayers can be purchased at your retail store. Pump sprayers may be used but may not provide the best results because the pressure can be inconsistent. So, a battery powered sprayer can be better.
An example is the Ryobi. This type of backpack sprayer comes with two nozzle types. This includes a conical and flat fan nozzle. Either one will work well. It can be purchased at many landscape supply centers, including at HomeDepot. (Geoponics, the makers of Endurant Turf Colorants have no association with this product or business. We just know many would call it the best sprayer for painting grass, especially when starting a lawn painting business.)
The backpack sprayer that is most recommended for the early grass painting professional is the Ryobi. You can see it here. For $200, give or take, it's a modest investment to launch a business with a sprayer and a gallon of paint. This type of sprayer also comes with two nozzle types: conical and flat fan nozzles. Either one will work well. Conical may be the most forgiving when it comes to overlapping the spray pattern for a new painter.
Sprayers can range from two-gallon hand pumps to GPS controlled spray rigs depending upon the job. A battery powered backpack sprayer is perhaps the ideal choice for painting grass with Endurant Turf Colorants.
Small area recommendations include backpack sprayers, the Pro Edge sprayer and/or Spray Hawks. Turf professionals covering large areas will find great results with Toro Low Profile 200-300 gallon, John Deere 200-300 gallon and/or Tractor, 3-point hitch pump operating from PTO 100-200 gallons.