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