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