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