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