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