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