One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,5)(6,8)(9,10)(11,23)(12,15)(13,20)(14,33)(16,21)(17,22)(18,25)(19,31)(24,34)(26,36)(27,28)(29,32)(30,38)(35,40)(37,39) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,11,15,25,17,27,16,26)(10,18,21,23,22,36,12,28)(13,30,31,40,32,39,14,24)(19,37,20,35,33,38,29,34)(2,5)(6,7)(9,12,16,22,17,21,15,10)(11,18,25,23,27,36,26,28)(13,20,14,19,32,29,31,33)(24,35,30,38,40,34,39,37)(1,3,4,8)(2,6,5,7)(9,13,16,14,17,32,15,31)(10,19,12,29,22,33,21,20)(11,24,25,30,27,40,26,39)(18,34,23,37,36,35,28,38)(9,14,15,13,17,31,16,32)(10,20,21,33,22,29,12,19)(11,24,25,30,27,40,26,39)(18,35,23,38,36,34,28,37)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.