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