This is meant to be the first strip of the storyboard detailing the sad part of the story, as the grape is left behind by the Hand and the light happiness of the world before is now gone.
The use of colours was more of a result of not wanting to colour it all properly and focusing in on what is important. what is important is the hero grape, and the golden light slowly leaving his world leaving behind only the cold grey of the lower part of the fridge.