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)(16,20)(21,23)(22,24)(25,26)(27,35)(28,34)(29,32)(30,36)(31,33)(37,40)(38,39)(2,3)(6,7)(9,11)(10,15)(12,21)(13,22)(14,20)(16,19)(17,23)(18,24)(25,27,31,29)(26,32,33,35)(28,36,38,37)(30,34,40,39)(1,3,5,2)(4,7,8,6)(11,20)(15,16)(21,24)(22,23)(26,33)(28,38)(32,35)(36,37)(1,4,5,8)(2,6,3,7)(9,11)(10,16)(12,21)(13,23)(14,20)(15,19)(17,22)(18,24)(25,28,31,38)(26,34,33,39)(27,37,29,36)(30,35,40,32)(9,12)(10,17)(11,21)(13,19)(14,18)(15,23)(16,22)(20,24)(25,29,31,27)(26,35,33,32)(28,36,38,37)(30,34,40,39)(9,13,14,17)(10,18,19,12)(11,22,20,23)(15,24,16,21)(25,30,31,40)(26,36,33,37)(27,34,29,39)(28,32,38,35)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.