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