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