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