The cover image was made using a program called neuroConstruct. Download and install the program. The networks repository contains detailed instructions for installing the program (on a Windows PC). In particular, an older version of Java (Java 8) is required to build and run the program.
Obtain the file called CElegans.ncx obtained from the CElegansNeuroML repository and load it into the program to generate a plot.
Rotate the plot to obtain a nice angle. I used this one for the cover. The team at Wiley did their adjustments to make it look as nice as it does.
Some screenshots I did not use are shown below:
