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