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