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