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