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