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