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