Add the Kool-Aid mix and sweetened condensed milk to a large bowl. Stir until the color is completely mixed in.
Fold in the whipped topping using a wooden or silicone spoon. Don't stir. Fold until there aren't any white streaks left.
Pour the mixture into the graham cracker crust and spread out evenly. Be gentle.
Refrigerate for at least 1 hour before slicing and serving.
