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