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