Steven Johnson's telling of this story is illustrative and to the point. Yet, as far as the single slide goes, it would have been far more effective had it been larger. It is always such a shame when a presenter has to say something like "You can't really see it here, but if you look...." I like the idea of using just the famous map here as the only visual. But at that relatively small size, the impact of the map was reduced a bit. Always good advice: make your visuals big.
Each black bar represents a death at the residence; deaths cluster near the Broad Street pump. See larger map here in better resolution.