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