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