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