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