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