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