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