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