Question

how do you find the original graph given this derivative graph?

Answer 1

the derivative tells you the slope of the tangent line. in this case the derivative is 3 constants. so your original function consists of 3 lines. one with positive slope, one with 0 slope ( a horizontal line) and one with negative slope.
you cannot know exactly where the function is, only what the slopes are

Answer 2

so it could look like this

Answer 3

but it need not be continuous. it could also look like