Cool on wire rack.
Slice horizontally into 3 layers. Set aside.
Sprinkle gelatin over cold water and lime juice in small saucepan. Let stand 1 minute. Stir over low heat until gelatin is completely dissolved, about 3 minutes.
Thoroughly combine pureed cantaloupe, gelatin mixture, sugar, lime zest and extract. Chill, stirring occasionally, until mixture mounds slightly when dropped from spoon, about 20 minutes. Stir in whipped topping.
Alternately layer angel food cake layers with cantaloupe mixture in 10 inch tube pan, ending with cake layer.
Chill until set, at least 3 hours.
To serve, run a long metal spatula around edges of pan. Unmold onto serving plate and garnish with mint.
Makes 12 servings.