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