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