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