  Multipartite Einstein-Podolsky-Rosen steering is an essential resource for
quantum communication networks where the reliability of equipment at all of the
nodes cannot be fully trusted. Here, we present experimental generation of a
highly versatile and flexible repository of multipartite steering using an
optical frequency comb and ultrafast pulse shaping. Simply modulating the
optical spectral resolution of the detection system using the pulse shaper,
this scheme is able to produce on-demand 4, 8 and 16-mode Gaussian steering
without changing the photonics architecture. We find that the steerability
increases with higher spectral resolution. For 16-mode state, we identify as
many as 65534 possible bipartition steering existing in this intrinsic
multimode quantum resource, and demonstrate that the prepared state
steerability is robust to mode losses. Moreover, we verify four types of
monogamy relations of Gaussian steering and demonstrate strong violation for
one of them. Our method offers a powerful foundation for constructing quantum
networks in real-world scenario.

Quantum Physics