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