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