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