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