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