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