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