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