Dissolve lemon gelatin in 1 cup boiling water; stir in 1/2 cup ginger ale. Set aside 1 cup gelatin and chill until thickened. Stir 1/2 cup whipped topping into remaining dissolved gelatin; chill until thickened. Repeat with orange, then strawberry gelatin. In 6-cup mold, layer creamy gelatin and clear lemon gelatin. Repeat with orange, then strawberry gelatin to form a total of 6 layers. Chill until firm, about 4 hours. To serve, unmold onto serving dish; garnish with mint sprig.
