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)(11,16,21,24)(12,17,22,20)(13,18,23,19)(25,26)(27,31)(28,30)(29,32)(33,35)(34,39)(36,37)(38,40)(1,3,5,8)(2,6,4,7)(25,26,30,28)(27,33,35,31)(29,32,37,36)(34,40,38,39)(10,15)(13,23)(16,24)(17,20)(26,28)(29,37)(31,33)(34,38) involution — undirected(9,11)(10,16)(12,18)(13,20)(14,21)(15,24)(17,23)(19,22)(25,27)(26,31)(28,33)(29,38)(30,35)(32,40)(34,37)(36,39) involution — undirected(9,12)(10,17)(11,19)(13,16)(14,22)(15,20)(18,21)(23,24)(25,28,30,26)(27,33,35,31)(29,36,37,32)(34,40,38,39)(1,4,5,2)(3,7,8,6)(9,13)(10,18)(11,20)(12,16)(14,23)(15,19)(17,21)(22,24)(25,29)(26,32)(27,34)(28,36)(30,37)(31,39)(33,40)(35,38)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.