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