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