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