  The Warm-Hot Intergalactic Medium (WHIM) is believed to host a significant
fraction of the ``missing baryons'' in the nearby Universe. Its signature has
been detected in the X-ray absorption spectra of distant quasars. However, its
detection in emission, that would allow us to study the WHIM in a systematic
way, is still lacking. Motivated by the possibility to perform these studies
with next generation integral field spectrometers, and thanks to the
availability of a large suite of state-of-the-art hydrodynamic simulations --
the CAMELS suite -- we study here in detail the emission properties of the WHIM
and the possibility to infer its physical properties with upcoming X-ray
missions like Athena. We focused on the two most prominent WHIM emission lines,
the OVII triplet and the OVIII singlet, and build line surface brightness maps
in a lightcone, mimicking a data cube generated through integral field
spectroscopy. We confirm that detectable WHIM emission, even with next
generation instruments, is largely associated to galaxy-size dark matter halos
and that the WHIM properties evolve little from $z\simeq0.5$ to now. Some
characteristics of the WHIM, like the line number counts as a function of their
brightness, depend on the specific hydrodynamic simulation used, while others,
like the WHIM clustering properties, are robust to this aspect. The large
number of simulations available in the CAMELS datasets allows us to assess the
sensitivity of the WHIM properties to the background cosmology and to the
energy feedback mechanisms regulated by AGN and stellar activity. [ABRIDGED]
