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