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