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