How to find out whether it is a positive or negative $\pi$ phrase between 00 and 11 from q-Sphere diagram?
As per @epelaaez's answer: the node color indicates the relative phase. However, there is a subtle point here.
As stated in this page, if you run this code snippet
Ψ = [8 / 17, 0, 0, 15j / 17] plot_state_qsphere(Ψ, show_state_phases = True)
the result will be
You can see that $|11⟩$ is displayed with phase = $0$ although it has a phase greater than zero. On the other hand, $|00⟩$ is displayed with a phase while it does not have one! This is because
plot_state_qsphere function removes the phase from the term with maximum probability, and normalizes the phases of other terms accordingly.