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