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