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