Answer
$y^{2}=-32x$
Work Step by Step
If focus of parabola is $F(p,0)$ this parabola has a horizontal axis
If focus of parabola is $F(0,p)$ this parabola has a vertical axis
In this case parabola has horizontal axis
$y^{2}=4px=4\times \left( -8\right) \times x=-32x$
