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