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