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