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