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)(25,26,31,30)(27,34,32,28)(29,37,38,33)(35,36,39,40)(1,3)(2,6)(4,7)(5,8)(9,11,15,13)(10,16,17,19)(12,20,23,21)(14,18,24,22)(25,27,31,32)(26,28,30,34)(29,35,38,39)(33,36,37,40)(1,2)(3,4)(5,7)(6,8)(10,17)(12,23)(16,19)(20,21)(25,28,31,34)(26,32,30,27)(29,36,38,40)(33,39,37,35)(1,3,5,8)(2,6,7,4)(9,12,15,23)(10,18,17,22)(11,21,13,20)(14,19,24,16)(25,27)(26,28)(29,35)(30,34)(31,32)(33,36)(37,40)(38,39)(1,2)(3,6)(4,8)(5,7)(9,13,15,11)(10,19,17,16)(12,20,23,21)(14,18,24,22)(25,29,31,38)(26,33,30,37)(27,35,32,39)(28,36,34,40)(1,4,5,6)(2,3,7,8)(9,14,15,24)(10,20,17,21)(11,18,13,22)(12,16,23,19)(25,30,31,26)(27,34,32,28)(29,37,38,33)(35,40,39,36)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.