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