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