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