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