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