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)(12,18)(13,23)(14,16)(15,21)(19,20)(22,24)(27,33)(31,38)(34,36)(39,40)(2,3)(6,7)(9,11)(10,15)(12,19)(13,20)(14,21)(16,17)(18,24)(22,23)(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)(13,18)(15,17)(20,24)(26,30)(31,38)(32,35)(39,40)(1,4)(2,6)(3,7)(5,8)(9,11)(10,17)(12,22)(13,20)(14,21)(15,16)(18,24)(19,23)(25,27)(26,31)(28,36)(29,33)(30,38)(32,40)(34,37)(35,39) involution — undirected(9,12)(10,18)(11,19)(13,16)(14,23)(15,24)(17,20)(21,22)(25,28)(26,32)(27,34)(29,37)(30,35)(31,39)(33,36)(38,40) involution — undirected(9,13,14,18)(10,12,16,23)(11,20,21,24)(15,19,17,22)(25,26)(27,31)(28,32)(29,30)(33,38)(34,39)(35,37)(36,40)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.