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)(11,14)(12,16)(13,15)(17,21)(18,20)(19,22)(23,24)(25,26)(27,36)(28,31)(29,33)(30,35)(32,39)(34,37)(38,40) involution — undirected(2,6)(7,8)(9,11,13,17)(10,14,15,21)(12,18,19,23)(16,20,22,24)(25,27,37,38,30,39,29,28)(26,31,33,32,35,40,34,36)(1,3,5,4)(2,7,6,8)(10,15)(11,17)(16,22)(18,23)(25,28,29,39,30,38,37,27)(26,32,34,31,35,36,33,40)(1,4,5,3)(2,8,6,7)(12,19)(16,22)(18,23)(20,24)(25,29,30,37)(26,33,35,34)(27,38,39,28)(31,36,40,32)(9,12,13,19)(10,16,15,22)(11,18,17,23)(14,20,21,24)(25,29,30,37)(26,33,35,34)(27,28,39,38)(31,32,40,36)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.