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