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