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