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