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