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