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