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