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