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