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