It's an imperialism cartoon. In which England (the octopus) grabs the corners of every continent in the world.
Octopus represents the avatar of imperialism, and the octopus was not just used externally to criticize an opposing or competitive nation’s policies, but also internally on a partisan basis, particularly in America and Britain. This cartoon represents greedy capitalistic monopolists.
England never needed more colonies, but did want them. The more land that was absorbed into the British Empire, the stronger the British hold upon global affairs would be and the more say they would have in what happened in the world.
If you need more help just ask :)