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