In a small bowl, mix together the graham cracker crumbs and sugar. Add the melted butter and toss with a fork or your fingers to combine. If using 8-ounce jars, lightly press 3 heaping tablespoons of the graham cracker mixture onto the bottom and up the sides of each jar. If using 4-ounce jars, use 2 level tablespoons. Set the jars aside.

In a large bowl, gently fold together the COOL WHIP and sweetened condensed milk. Add the lemonade concentrate. If desired, add the lemon juice and food coloring. Evenly distribute the filling among the jars. Cover and freeze for at least 4 hours. When ready to serve, allow to stand for 5 minutes.