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