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