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)(11,13)(12,16)(14,17)(15,18)(19,21)(20,23)(22,24)(27,32)(29,34)(30,38)(33,36)(2,3)(6,7)(9,11,15,12)(10,16,18,13)(14,19,22,20)(17,23,24,21)(25,26,31,28)(27,34,32,29)(30,33,38,36)(35,40,39,37)(1,3,5,2)(4,7,8,6)(9,11,15,12)(10,13,18,16)(14,19,22,20)(17,21,24,23)(25,27)(26,29)(28,34)(30,35)(31,32)(33,37)(36,40)(38,39)(1,4,5,8)(2,6,3,7)(9,12,15,11)(10,13,18,16)(14,19,22,20)(17,23,24,21)(25,28,31,26)(27,34,32,29)(30,33,38,36)(35,37,39,40)(9,13)(10,12)(11,18)(14,21)(15,16)(17,20)(19,24)(22,23)(25,29,31,34)(26,32,28,27)(30,37,38,40)(33,39,36,35)(9,14)(10,17)(11,19)(12,20)(13,21)(15,22)(16,23)(18,24)(25,30,31,38)(26,33,28,36)(27,35,32,39)(29,37,34,40)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.