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