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