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