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