Graphing complex numbers use a Real-Imaginary plane.
I think you want to graph the function on the x-y plane?
if so
Are you sure you have understood the directions correctly? Just graphing a complex number, a+ ib, requires two dimensions. Graphing a function, y= f(x), where both x and y are complex numbers, requires two dimensions for both variables- you would need a four dimensional graph! If you take x to be real only, you would need a three dimensional graph which is at least possible. If you take the x-axis to be the real x variable, you can let the y-axis be the real part of f(x), and the z axis be the imaginary part.
Now for , with x real, y is real for , pure imaginary for x< 0. So for you will have just the graph of in the xy-plane. For x< 0, [tex]\sqrt{x}= \sqrt{-1|x|}= i\sqrt{|x|}. The graph will be turned 90 degrees at x= 0 and will be the graph of in the xz- plane.