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)(12,20,21,15)(14,22,23,19)(25,26)(27,35)(28,34)(29,33)(30,32)(31,38)(36,40)(37,39)(2,5)(6,8)(12,21)(14,23)(15,20)(19,22)(25,27)(26,31)(28,37)(29,38)(30,36)(32,39)(33,35)(34,40) involution — undirected(1,3,4,7)(2,6,5,8)(9,11,13,18)(10,14,16,23)(12,22,21,19)(15,24,20,17)(26,32)(27,36)(28,30)(33,34)(37,38)(39,40)(2,5)(6,8)(11,18)(14,23)(17,24)(19,22)(25,28,29,30)(26,32,33,34)(27,37,38,36)(31,39,35,40)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.