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