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