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