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