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