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