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