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