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