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