There are three things I would've done differently here.
1) The graffiti is very small compared to the size of the frame. This alone takes from it's significance. Make it bigger in the frame. You do not need to show the whole building, it's a very repetitive shape so you can easily convey the building with just a proportion of the repetition. Definitely loose the distracting buildings to the left and right.
2) It was shot with a wide angle pointing up. You're introducing a lot of exaggerated perspective here. With a tighter crop you could've moved away a little with a longer focal length lens.
3) Your main point of interest is in the shadow. It really needs to be brighter. Fortunately you can make the figure little brighter without making the image look unreal, this brings your eye to the right spot (obviously you can't make black lettering brighter).
So making it bigger, reducing the distortion, increasing the relative brightness, and introducing a composition that places the main interest on a strong diagonal, I came up with this: