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