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