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