Basic method to generate this set if you want to play around with it:

    from itertools import chain
    import numpy as np
    import matplotlib
    matplotlib.use('TkAgg')
    from matplotlib import pyplot as plt

    def gen_pm_one(m):
        def array_for(n):
            return map(
                lambda i: 1 if not (1 << i) & n == 0 else -1,
                range(m)
            )

        def out():
            generated = 0
            final = 2 ** m

            while generated < final:
                yield array_for(generated)
                generated += 1

        return out()

    if __name__ == '__main__':
        roots = map(
            lambda roots: map(
                lambda cpx: [cpx.real, cpx.imag],
                roots
            ),
            map(
                np.roots,
                gen_pm_one(13)
            )
        )

        data = np.array(list(chain(*roots)))
        x, y = data.T
        plt.scatter(x,y)
        plt.show()