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