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