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