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