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