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