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