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