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