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