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)(25,26,31,36)(27,33,38,40)(28,39,37,32)(29,35,30,34)(9,11)(10,14)(12,19)(13,18)(15,23)(16,22)(17,20)(21,24)(25,27,31,38)(26,32,36,39)(28,29,37,30)(33,35,40,34)(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)(26,32)(27,30)(29,38)(31,37)(33,35)(34,40)(36,39)(11,18)(14,22)(17,19)(21,23)(25,27)(26,33)(28,29)(30,37)(31,38)(32,34)(35,39)(36,40) involution — undirected(1,4,5,3)(2,6,7,8)(10,16)(14,22)(15,24)(21,23)(25,29,31,30)(26,34,36,35)(27,37,38,28)(32,33,39,40)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.