In a small bowl, dissolve cherry gelatin in 1 cup boiling water; stir in 1/2 cup cold water. Pour into an 8-in. square dish coated with cooking spray. Refrigerate until set.
Repeat with lime and orange gelatin, using separate 8-in. square dishes for each.
In a large bowl, dissolve lemon gelatin and sugar in remaining boiling water; stir in lemonade. Cover and refrigerate until slightly thickened. Fold in whipped topping.
Cut the cherry, lime and orange gelatin into 1/2-in. cubes. Fold into lemon gelatin mixture. Spoon into individual serving dishes. Cover and refrigerate for at least 2 hours. Garnish with additional whipped topping if desired.