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