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