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