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