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