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