The easiest way that does not require any Python scripting is to use the command line program (see https://toughio.readthedocs.io/en/latest/cli.html#export):
In your terminal or console (not Python IDE such as Spyder), cd to your simulation directory where your OUTPUT_ELEME.csv is located, and run:
toughio-export OUTPUT_ELEME.csv -t int
where `int` stands for the time step number you want to export (by default the last time step `-1`). This command will create a VTK file that you can simply drag and drop to ParaView (https://www.paraview.org/) for visualization.
If you want all the time steps in the same file and kind of animate your results, append the option `-f xdmf`:
toughio-export OUTPUT_ELEME.csv -f xdmf
You can open the XDMF file in ParaView too.