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