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