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