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