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