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