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