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