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