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