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