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