#### Answer

The graph is a circle whose center is at $(0,4)$ with radius $4$.

#### Work Step by Step

Conversion of polar coordinates and Cartesian coordinates are as follows:
a) $r^2=x^2+y^2 \implies r=\sqrt {x^2+y^2}$
b) $\tan \theta =\dfrac{y}{x} \implies \theta =\tan^{-1} (\dfrac{y}{x})$
c) $x=r \cos \theta$
d) $y=r \sin \theta$
Here, we have $r^2=8r \sin \theta $
Therefore, our Cartesian equation is $x^2+y^2=8y \implies x^2+(y-4)^2=16$
This shows that the graph is a circle whose center is at $(0,4)$ with radius $4$.