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