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