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