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