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