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