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