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