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