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