I have seen this graph many times.
From the graph, it would seem that if you calculate the gravitational potential at any given point you obtain a negative, and if you calculate the field strength at the same point you obtain a positive, suggesting the two are in opposite directions.
But, if $g=-\frac{dV}{dr}$, then by using the expression that $V=-G\frac{M}{r}$ and differentiating with respect to r, you should obtain:
$-\frac{d}{dr}\,(-GMr^{-1})\,=\,-\,-1\times-GMr^{-2}\,=\,-G\frac{M}{r^{2}}\,=\,-g.$
Therefore you would expect g to be negative, and so the curve for gravitational field strength would be in the lower half of the graph.
Is this correct?