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