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