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