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