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