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