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