One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,3)(5,6)(7,8)(9,10)(11,21)(12,26)(13,20)(14,18)(15,19)(16,24)(17,28)(22,31)(23,30)(25,32)(27,34)(29,33)(35,37)(36,40)(38,39)(1,3,4,2)(9,11,13,24,15,22,14,25)(10,16,18,21,19,32,20,31)(12,23,27,38,29,36,28,37)(17,30,33,35,34,40,26,39)(2,3)(11,22)(12,27)(13,14)(17,33)(18,20)(21,31)(23,37)(26,34)(28,29)(30,35)(36,38)(39,40) involution — undirected(6,8)(9,12,13,27,15,29,14,28)(10,17,18,33,19,34,20,26)(11,23,24,38,22,36,25,37)(16,30,21,35,32,40,31,39)A 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.