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