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