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