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