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