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