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