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