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