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