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