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