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