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