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