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