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