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