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