Onyango spent his early years living with his family near the coast, where his father was involved in a growing industrial development. He developed a fascination with the machinery that surrounded him, including bulldozers, tractors, trucks, and planes, which continue to serve as backdrops in his paintings. These images are often associated with drama and disaster and are painted entirely from memory, creating a feeling of helplessness in the viewer as they witness the stories being portrayed on canvas or board.