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