Cut cake loaf horizontally into 3 layers. Place bottom layer on serving tray.
Spread 1 cup of sorbet over cake layer. Top with center cake layer; spread with remaining 1 cup of sorbet. Repeat with last cake layer.
Sprinkle top with coconut. Wrap loosely in foil; freeze at least 1 hour before serving. If desired, serve slices with cut-up fresh or purchased refrigerated mango.