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