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