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