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