Chocolate gelatin: Sprinkle gelatin over 1/2 cup cold water in a bowl; let stand until softened, 5 minutes. Bring cream, sugar, salt, and cocoa to a simmer in a medium saucepan, stirring until sugar and cocoa are dissolved. Stir in chocolate until smooth. Add gelatin mixture; stir until dissolved. Remove from heat.
Coconut gelatin: Sprinkle gelatin over 1/2 cup cold water in a bowl; let stand until softened, 5 minutes. Add boiling water; stir until gelatin is dissolved. Stir in cream of coconut.
Whisk each gelatin; strain separately through a fine sieve. Add a layer of either chocolate or coconut gelatin to each of ten 6-to-8-ounce glasses; refrigerate until set, 1 to 3 hours. Continue adding layers, alternating flavors each time and letting each layer set before adding next; pour through sieve slowly and carefully when topping layers. (Reheat as needed to keep gelatins pourable.) Refrigerate assembled gelatins at least 2 hours and up to 3 days before serving, topped with whipped cream.