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