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