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