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