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