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