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