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