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