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