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