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