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