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