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