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