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