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