The LHCb collaboration have recently updated their analysis of the resonant \(J/\psi p\) mass spectrum in the decay \(\Lambda_b^0 \to J/\psi p K^-\), making use of their combined Run 1 and Run 2 data. In the updated analysis, three narrow states, \(P_c (4440)^+\), \(P_c (4457)^+\),and \(P_c (4312)^+\), are observed. The spin-parity assignments of these states are not yet known. We interpret these narrow resonances as compact hidden-charm diquark-diquark-antiquark pentaquarks. Using an effective Hamiltonian, based on constituent quarks and diquarks, we calculate the pentaquark mass spectrum for the complete \(SU (3)_F\) lowest \(S\)- and \(P\)-wave multiplets, taking into account dominant spin-spin, spin-orbit, orbital and tensor interactions. The resulting spectrum is very rich and we work out the quark flavor compositions, masses, and \(J^P\) quantum numbers of the pentaquarks. However, heavy quark symmetry restricts the observable states in \(\Lambda_b\)-baryon, as well as in the decays of the other weakly-decaying \(b\)-baryons, \(\Xi_b\) and \(\Omega_b\). In addition, some of the pentaquark states are estimated to lie below the \(J/\psi p\) threshold in \(\Lambda_b\)-decays (and corresponding thresholds in \(\Xi_b\)- and \(\Omega_b\)-decays). They decay via \(c \bar c\) annihilation into light hadrons or a dilepton pair, and are expected to be narrower than the \(P_c\)-states observed. We anticipate their discovery, as well as of the other pentaquark states present in the spectrum at the LHC, and in the long-term future at a Tera-\(Z\) factory.