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)(26,31)(27,34)(33,36)(35,40) involution — undirected(2,5)(6,7)(11,17)(15,21)(18,23)(22,24)(25,26,30,31)(27,32,34,29)(28,36,38,33)(35,39,40,37)(1,2)(3,6)(4,5)(7,8)(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)(25,27)(26,32)(28,35)(29,31)(30,34)(33,37)(36,39)(38,40) involution — undirected(1,2)(3,7)(4,5)(6,8)(9,11,13,17)(10,15,14,21)(12,18,20,23)(16,22,19,24)(25,28,30,38)(26,33,31,36)(27,35,34,40)(29,39,32,37)(1,3)(2,6)(4,8)(5,7)(9,12)(10,16)(11,18)(13,20)(14,19)(15,22)(17,23)(21,24)(25,29,30,32)(26,27,31,34)(28,37,38,39)(33,40,36,35)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.