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