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