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