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