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