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)(27,36)(28,32)(29,34)(30,35)(31,39)(33,38)(37,40) involution — undirected(1,2,5,6)(3,7,8,4)(9,11,14,17)(10,15,13,19)(12,18,20,21)(16,23,22,24)(25,27)(26,31)(28,29)(30,39)(32,40)(33,34)(35,36)(37,38)(1,2)(3,7)(4,8)(5,6)(10,13)(11,17)(12,20)(23,24)(25,28,30,38)(26,32,35,33)(27,29,39,37)(31,40,36,34)(2,6)(3,8)(9,11)(10,15)(12,21)(13,19)(14,17)(16,24)(18,20)(22,23)(25,28)(26,33)(27,37)(29,39)(30,38)(31,40)(32,35)(34,36) involution — undirected(1,3)(2,4)(5,8)(6,7)(9,12)(10,16)(11,18)(13,22)(14,20)(15,23)(17,21)(19,24)(25,29,30,37)(26,34,35,40)(27,38,39,28)(31,32,36,33)(1,4)(2,3)(5,7)(6,8)(9,13,14,10)(11,19,17,15)(12,22,20,16)(18,24,21,23)(25,26)(27,31)(28,33)(29,34)(30,35)(32,38)(36,39)(37,40)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.