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