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