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