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)(11,13)(12,16)(14,18)(15,17)(19,21)(20,23)(22,24)(25,26)(27,31)(28,36)(29,34)(30,32)(33,38)(35,40)(37,39)(1,3,5,8)(2,6,4,7)(9,11,15,12)(10,16,17,13)(14,20,22,19)(18,21,24,23)(25,27,30,29)(26,31,32,34)(28,35,38,37)(33,39,36,40)(10,17)(11,12)(14,22)(21,23)(26,32)(31,34)(33,36)(39,40) involution — undirected(1,2,5,4)(3,6,8,7)(9,12,15,11)(10,16,17,13)(14,20,22,19)(18,23,24,21)(25,26)(27,31)(28,33)(29,34)(30,32)(35,39)(36,38)(37,40)(1,2,5,4)(3,6,8,7)(9,13,15,16)(10,12,17,11)(14,21,22,23)(18,20,24,19)(25,28)(26,33)(27,35)(29,37)(30,38)(31,39)(32,36)(34,40)(1,4,5,2)(3,7,8,6)(9,14)(10,18)(11,19)(12,20)(13,21)(15,22)(16,23)(17,24)(25,29,30,27)(26,34,32,31)(28,37,38,35)(33,40,36,39)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.