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