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