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