The 'Canary Yellow" Diamonds & Pearls Cloud Guitar as it was known then. Canary yellow was his "era/theme color" for that period, much like Purple was for 1999 through Purple Rain and Peach & Black was for the Camille/SOTT/Black Album era.
an enso represents a journey. Buddhist monks draw these with brushes in journals; an open enso signifies an ongoing journey. In Zen Buddhist painting, ensō symbolizes a moment when the mind is free to simply let the body/spirit create.