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