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