Mix graham cracker crumbs and butter together in a bowl until crumbs are evenly moistened. Press over the bottom of a 9x13-inch baking pan to make a crust.
Mix cream cheese, whipped topping, and 1 cup sugar together in a bowl until smooth. Spread evenly over crust.
Combine 1 cup sugar, water, cornstarch, and salt in a saucepan over medium heat; cook and stir until clear, 3 to 5 minutes. Stir in mashed huckleberries, lemon juice, and red food coloring; simmer until thickened, about 5 minutes.
Spread huckleberry mixture over cream cheese layer. Scatter whole huckleberries on top.