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