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