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