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