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