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