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