Determine and draw planes and axes of symmetry of a molecule using software (VESTA or Mercury)
I do not know VESTA well enough to provide an answer for this program.

However because your data are about a crystal structure I suggest to export your model in the .cif format.  CCDC's freely available version of CCDC's Mercury is able to read this file type, and add to its visualizations the symmetry elements of the unit cell (Display -> Symmetry Elements).  There will be a new menu where you may choose among the symmetry elements the program is able to recognize, and how they are displayed:



For example only the centres of inversion:



The export options in Mercury include bitmap .png, ray-tracing PovRay .pov, and .vrml / .stl.



Given lattice constants and space group $P6_3/mmc$, do not forget to compare your model with the literature known models for example in the freely accessible COD about experimental data (entries #1010993, #1011286, #1531960, #9007660, #9009144); and consider contributing to its sibling TCOD about theoretical data and MPOD.