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