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