The horizontal axis shows the go rating scale used by the EGD and the revised rating system.
The vertical axis shows points change.
The upper and lower lines bound the maximum rating points change for wins and losses. It is determined by the con factor and the bonus term.
The middle line is the contribution of the bonus term. You may have to zoom in (at the lower ratings) to see its contribution.
The FIDE chess rating system uses a K factor, which basically works the same as the con factor. They mostly use 20, but for youth players and new players they use 40. For high ratings they use 10. (also see the FIDE rating calculator) Other chess rating systems use K factor 24 with 16 for high ratings and 32 for low ratings. So the EGD uses a rather high value for low ratings.
Anyway, I chose to reduce the rating volatility by reducing the con factor for lower ratings to allow detection of deflation signals.