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