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