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