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