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