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