Make cake banner. For banner triangles, roll out pink, orange, yellow and purple fondant, separately, 1/16 in. thick. Cut 13 triangles in each color, 5/8 in. high x 5/8 in. wide. Use damp brush to attach triangles to cake, against edge of banner strings.
Use black FoodWriter edible color marker to color two lollipop sticks. Insert sticks on an angle in top of cake. Cut one 7 in. piece of floss and one 9 in. piece. Tie floss to sticks. For banner, roll out remaining neon fondant colors, separately, 1/16 in. thick. Cut three diamonds in each color, 1 1/2 in. long x 3/4 in. wide at center. Fold diamonds over floss, alternating colors.