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