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