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