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