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