In a large bowl, add ice cream, lemonade, whipped topping, zest, and 1/2 tsp food coloring. Add more food coloring if needed to reach desired color. Stir until combined well. (Using a stand mixer works really well)
Pour mixture into graham cracker crust. Spread evenly.
Freeze until firm, about 4 hours. Garnish with lemon peel and extra whipped topping if desired.