For the picture I indicated centrality through the size of the node (the circle and username), so the larger the username = the more central. The physical position of each node doesn't really mean anything other than to separate out the bigger from smaller nodes and make it look pretty. But... the fact that you can even see your username given how many users there are in the graph (8,500+) means you're pretty central to it. You might find that surprising since you have less than 50 followers, but you're actually in the top 30 for most central users.