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