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