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