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