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