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