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