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