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