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