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