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