Gaugin's (wiki) art, while having depth, also did things like contain certain colors within certain areas, paint the ground pink and the trees blue etc. Araki loved Gauguin's art ever since he was a child, and has been deeply influenced by him. When Jojo became an OVA, one of the animators asked Araki "what color if Jotaro?" however Araki had no such concept. He colors everything based on calculation. For example, in Volume 54 Giorno's clothes are pink, but in Volume 63 they are blue. Also, regarding the color cover illustration, he explains that placing the color blue beside pink exudes more power. He says that he gets his inspiration from 80's art, shading techniques in Western art, classical paintings and gets inspiration for his various poses from sculptures. All of this research, blended with Araki's own personality, result in Jojo's art style.