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