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