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