One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,4)(9,10,13,18,14,20,31,19)(11,21,22,36,25,37,24,16)(12,26,29,17,30,15,27,33)(23,34,38,40,28,35,39,32)(5,6)(7,8)(10,15)(11,22)(12,27)(13,31)(16,34)(17,18)(19,33)(20,26)(21,32)(23,28)(24,25)(29,30)(35,36)(37,40) involution — undirected(2,4)(6,8)(9,11)(10,16)(12,28)(13,24)(14,25)(15,32)(17,34)(18,37)(19,21)(20,36)(22,31)(23,30)(26,40)(27,39)(29,38)(33,35) involution — undirectedA Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.