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