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