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